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GALVANIZING 

AND 

TINNING 

A Practical Treatise on the Coating of 

Metal with Zinc and Tin by the Hot 

Dipping, Electro Galvanizing, Sher- 

ardizing and Metal Spraying 

Processes, with Information on 

Design, Installation and 

Equipment of Plants. 




By W^TF FLANDERS 

Malleable Iron Fittings Co. 

With the Assistance of the following Specialists 



John Cai.der, 
R. D. Foster, 
C. J. Kirk, 
a. f. schoen, 
Louis Schulte, 
Wm. G. Stratton, 
Samuel Trood. 



Metal Coatings Co. of America 
Hanson & Van Winkle Co. 
U. S. Sherardizing Co. 
New Haven Sherardizing Co. 
Ele-Kem Co. 
R. N. Bassett Co. 
Consulting Engineer 



U. P. C. BOOK COMPANY, Inc. 
243 W. 39tJi St. Nf.w York 

Reprinted 1922 









Copyrighted 1916 
By 
DAVID WILLIAMS COMPANY 



Copyrighted 1922 
By the 
U. P. C. BOOK COMPANY. Inc. 







Printed in U. S. A. 



JUN 13 1922 

(am AB77127 



PREFACE 

THE original work "Galvanizing and Tinning" was prepared 
to meet the demand for reliable information on the meth- 
ods of protecting iron and steel from corrosion which the 
editors of the Metal Worl-er and Tlie Iron Age were continually 
receiving. Mr. Flanders, who had specialized on the hot dipping 
processes of coating with zinc and tin for many years, was induced 
to describe the proper design and equipment of plants and the 
methods he had found most satisfactory. 

Since it was published, many improvements have been made in 
the hot galvanizing and tinning processes. Several new methods 
of utilizing zinc and tin for protection against corrosion have also 
))een devised and perfected. Mr. Flanders did not feel qualified 
to treat these new processes, and, as a majority of them are cov- 
ered by patents, it was difficult to obtain practical information 
regarding their application, as well as the design and installation 
of the apparatus. 

Several of the experts who had sj^ecialized on the new processes 
refused to contribute because they deemed their methods "trade 
secrets," while others supplied splendid advertising matter for their 
special process, but little practical data. 

The treatment of hot galvanizing and tinning is as compre- 
hensive and reliable as Mr. Flanders' practical experience could 
make it. This covers a period of over thirty-five years as mechanic, 
builder and manager of plants. He was ably assisted in this work 
by Mr. H. A. Smith, who contributed a large amount of data that 
is new. 

In revising the chapter on re-tinning, Mr. Flanders received 
much valuable assistance from Mr. AV. C. Holland, a former shop- 
mate, and from Mr. J. B. Smith, mechanical engineer, and Mr. 
W. E. Mumford, metallurgist. 

Many interesting and valuable articles by other experts, bearing 



•2 PREFACE 

on protective coating of zinc and tin, which have appeared in vari- 
ous trade papers, have been included and proper credit given in 
the text. 

The aim of all who have assisted in the preparation of this work 
has been to make it of the greatest practical value to the men 
actually engaged in the plant, as well as to those who are contem- 
plating the installation of plants. If the readers of the book fail 
to find the information they desire, the publishers will be pleased 
to have them submit the problems for the consideration of the 
experts who collaborated in making it so nearly complete. 

The Editor 

Nev/ York, May, 1922. 



TABLE OF CONTENTS 

CHAPTER I PAGE 

Corrosion and Its Prevention 9 

Tliporv of Corrosion— Galvanizing Proccssos Descrilicd — Zinc 
Coating tiie Best Rust Preventive — Hints on Selection of Em- 
ployees and Handling of Work and Equipment. 

CHAPTER II 
Hot Galvanizing Plant and Equipment 14 

Arrangement, Drainage and Ventilation of the Galvanizing Room 
— Tlie Equipment — Laws of Physics Applying to Hot Galvan- 
izing — The Selection of Proper Grades of Iron and Steel for a 
Kettle — Methods of Testing Material for Manufacture of Ket- 
tle — Sizes of Kettles for Different Work — Plans and Details of 
Construction for Different Style Kettles — Plan and Details of 
Construction of Arrangement for Drying Castings — Bricking In 
a Galvanizing Kettle — Tanks for Acid Solutions and Water — 
Tools for Galvanizing. 

CHAPTER III 
The Pyrometer 34 

Use of Pyrometer — Protecting Pyrometer from Action of Zinc — 
Proper Location of Pyrometer in Kettle — Temperature of Zinc 
Required to Secure Uniform Coatings — Selection of Pyrometer — 
Temperature Table and Method of Calculating Numbers of De- 
grees Drop Per Hour in Molten Zinc While Cooling — Correct 
INIethod of Using Tliermometer. 

CHAPTER IV 
Materials Used in Galvanizing 41 

Spelter — Lead — White and Gray Granulated Sal Ammoniac — 
Zinc Ammonium Chloride — Muriatic, Sulphuric and Hydro- 
fluoric Acids — Coke — Oil — Glycerine — Aluminum. 

CHAPTER V 
Pickling 44 

Securing Uniform Action with Acids — Mechanical Pickling — ■ 
Pickling Sheets — Over Pickling — LTnder Pickling- — Acid Con- 
simiption in Pickling — Removing Scale with Sulphuric Acid — 
Time Required for Removal of Scale — Removing Scale with 
Muriatic Acid — Substitutes for Acids — Cleaning Sandy Castings 
with Sulphuric Acid — Cleaning Castings with the Aid of Hydro- 
fluoric Acid — Temperature of Pickle — A "Quick" Pickle. 

CHAPTER VI 
Water Rolling, Tumbling and Sand Blasting ... 51 

W'ate^r Rolling — Dry Tumbling — Dcssign and Construction of 
Wet Tumbling Barrel — Preparing Castings for Tumlding — Load- 
ing Tumbling Barrel — Time Required to Clean Work in Tnm- 
bling Barrel — Mixtures for Cleaning Castings in Tumbling Bar- 
rel — Testing Castings to See if They are Properly Cleaned — 
Re-charging Tumbling Barrel — Handling Delicate Castings in 
Tumbling Barrel — Storing Castings After Tumbling — Prepairiug- 

3 



4 CONTENTS 

PAGE 
Work for Galvanizing or Tinning With the Sand Blast — Simple 
Home-made Type — Single Hose Type Apparatus — Two Hose Type 
Apparatus — Sand Blast Rolling Barrel — Air Pressures Re- 
quired in Sand Blasting — Construction and Ventilation of Sand 
Blasting Room — Condition of Sand — Diamond Grit and Steel 
Shot Used as Substitute for Sand — Preparing the Cleaned Work 
for the Dippings — Drying the Work. 

CHAPTER VII 

Hot Process of Galvanizing 66 

Filling a New Kettle — Firing a New Kettle — The Temperature 
of the Zinc — Dipping the Work in the Molten Zinc — Removal 
of Surplus Zinc — Drying and Cooling Work — Cost of Production. 

CHAPTER VIII 

Galvanizing Sheets 73 

Galvanizing Sheets by Hand — Construction of Davies Machine 
for Galvanizing Sheets — Davies Method- — Heathfield Method — 
Bayliss Process — Material Required to Galvanize Sheets. 

CHAPTER IX 

Galvanizing Wire, Netting and Tubes 77 

An Improvement in Galvanizing Wire Cloth — The Influence of 
Galvanizing on the Strength of Wire — Tests Used to Determine 
Strength of Wire — Absorbed Hydrogen Gas Does Damage — The 
Automatic Galvanizing of Tubes — Plan and Elevation of Ma- 
chine for Automatic Galvanizing of Tubes. 

CHAPTER X 

By-Products of the Hot Galvanizing Process ... 84 

Zinc Dross — Running Over or "Sweating" Zinc Dross — Plan and 
Details of Construction for Kettle Used in Recovering Zinc 
Dross — Sal Ammoniac Skimmings — Screening, Storage and Re- 
covery of Zinc Ashes. 

CHAPTER XI 

Replacing Old Galvanizing Kettles 92 

Life of Kettles — Repairing Leaks in Kettles — Tools for Boiling 
Out Kettles. 

CHAPTER XII 

The Schoop Metal Spray Process 94 

Evolution of Apparatus — Operation of Old Stationary Type — 
Details of Construction of Old Stationary Type^Operation of 
First Portable Type — Details of First Portable Type — Opera- 
tion of the Cyclone Apparatus — Details of Construction and 
Operation of Modern Spraying Pistol — Melting Point of Zinc and 
Tin in Schoop Process — Gas Pressure Required — Applying the 
Coating — Thickness of Deposit — Cost of Coating. 

CHAPTER XIII 
Tinning Malleable Iron Castings, Wrought Iron, and 

Steel . 106 

Plant and Equipment — Plan of a Tinning Plant — Tools and 
Kettles. 



CONTENTS 5 

PAGE 

CHAPTER XIV 

Preparing the Work for Tinning Ill 

Removing Scale and Rnst with Sulphuric Acid — Cleaning Sandy 
Castings with Sulphuric Acid — Cleaning with Muriatic Acid — 
Cleaning Sandy Castings with Hydrofluoric Acid — Water Rolling 
— Removing Paint or Grease. 

CHAPTER XV 

Applying the Coating of Tin 115 

Tinning with Two or More Kettles of Tin — Setting Up the 
Kettles — Passing the Work Through the Tinning Kettle — Tem- 
perature and Time Required — Tinning Wire in Coils — Tinning 
Steel Spoons and Similar Articles. 

CHAPTER XVI 

Re-Tinning 121 

Construction of Re-tinning Plan Having Four Kettles — Tools 
Required — Method of Handling Work — Use of Listing Kettle — 
Removal of Surplus Tin in Skimming Kettle — Finishing of Re- 
tinned Work — Replacing Re-tinning Kettles. 

CHAPTER XVII 

Tinning Gray Iron Castings 129 

Plans of Plants, Showing Arrangement of Equipment — Eleva- 
tions and Details of Constrviction of Kettles — Tools Required. 

CHAPTER XVIII 
preparing Gray Iron Castings for Tinning .... 133 

Removing Sand from the Castings — Freeing Gray Iron Castings 
from Sand by Hydrofluoric Acid — Cleaning Sandy Castings with 
Sulphuric Acid — Cleaning Castings with the Sand Blast — The 
Use of Hot Alkali Bath in Certain Cases — Tumbling — Water 
Rolling. 

CHAPTER XIX 

Coating Gray Iron Castings with Tin . . . . , . 138 

Dipping the Castings — Flux for Tinning Kettle — Handling Cast- 
ings in Roughing Kettle — Time Required to Tin Castings — Re- 
moval of Slag from Kettle — Proper Heat for Tinning — Construc- 
tion of Oil Tank — Tongs Used in Tinning — Construction and Use 
of Switching Box — Tinning with Three Kettles of Tin — Effect 
of Overheating — Storage of Dross. 



CHAPTER XX 

Cleaning Old Galvanized and Tinned Work .... 146 

Cleaning Old Galvanized Work — Refinishing Old Galvanized 
Work — Cleaning Old Tinned Work — Kettles for Refinishing Old 
Galvanized and Tinned Work. 



6 CONTENTS 

PAGE 

CHAPTER XXI 

Electro-Galvanizing Plant and Equipment .... 148 

Electro-Galvanizing — Equipment for Electro-Galvanizing Plant 
— Mechanical Galvanizing and Patented Devices — The Miller 
Chain Conveyer Machine — -Daniels Screw Conveyer Machine — 
The Fleischer Cable or Chain Conveyer Machine- — The Daniels 
Barrel— The Pothoif— The Schulte Barrel— The Ele-Kem Galvan- 
izing Barrel — A Cleaning, Rinsing and Plating Barrel Unit — 
Modified Form of the Cleaning, Rinsing and Plating Barrel Unit 
— The Meaker Continuous Type Machine — Hanson & Van Winkle 
Pipe and Tube Galvanizing Machine — The Pothoff Tube Galvan- 
izing Machine — King's Continuous Wire Clotli Machine — The 
Root Wire Cloth Machine — Schulte Wire Galvanizing Machine — 
Electrical Equipment — Anodes — Cost of Installation. 

CHAPTER XXn 

Preparing Work for Electro-Galvanizing 209 

Removing Sand from Castings — Removing Oil or Grease — Re- 
moving Mill Scale — Scratch-Brushing — Copper Flashing — Tum- 
bling and Sand Blasting — Schulte Grinding and Scouring Ma- 
chine — Electro-Cleaning. 

CHAPTER XXIII 

Electro-Galvanizing Solutions and Their Application . 217 

Composition of Galvanizing Solutions — Twenty-foTir Good For- 
mulas — Agents for Experimenting on or Improving Solutions — 
Modern Methods of Applying the Coatings — Cost of Operation — 
Tests for Thickness of Zinc Coating. 

CHAPTER XXIV 

The Art of Sherardizing 227 

Dry Galvanizing in Prehistoric Times — Theory of Sherardizing 
— How Precipitation of a Vapor on Metal Occurs — Methods of 
Producing Zinc Vapor. 

CHAPTER XXV 

Location and Equipment of the Sherardizing Plant . . 233 

Cleaning Apparatus — The Sherardizing Furnace or Oven — Coke 
Burning Furnaces — Gas and Oil Burning Furnaces — Electric 
Heated Furnaces — Wiring Diagrams — Drums — Dust Separating 
Machine— The Transfer Car — Cooling Frames — Pyrometers. 

CHAPTER XXVI 

Materials Used in Sherardizing 256 

Dvist from the Zinc Smelter — Freeing Dust from Iron — Use of 
ManufacturedsZinc Dust — Method No. 1 for Determining Metal- 
lic Zinc in Zinc Dust — ^Method No. 2 for Determining Metallic 
Zinc in Zinc Dust — Method No. 3 for Determining Metallic Zinc 
in Zinc Dust. 

CHAPTER XXVII 

Preparing Material and Loading 261 

Pickling of Steel — Pickling Malleable and Gray Iron Castings 
— Loading the Drums — Packing the Electric-Heated Drum. 



CONTENTS 7 

CHAPTER XXVIII page 

Temperature and Duration of Heats 267 

Tliickiiess of C()atini>- — Tcmporatnrc an Important Factor — 
Operation of the Electric-Heatod Drum — Slicrardi/.infjr with Zinc 
Under Vacuum — Time an Important Factor — Motion During 
Shcrardizing- — General Operation — Cooling and Unloadiny. 

CHAPTER XXIX 
Don'ts in Sherardizing Practice 278 

Eliminating Black Spots on Finished Work — Obviating Non- 
Uniformity of Coating — Improving Psychological Condition of 
Men— ^Caution — Don'ts. 

CHAPTER XXX 

Coloring and Finishing Sherardized Articles .... 282 

Bulling — (_'utting Down — Burnishing — Nickel — Copper — Bronze — 
Japanning — Enameling — Lacquering. 

CHAPTER XXXI 
Cost of Sherardizing Material Per Ton with Different 

Fuels . . . . ' 287 

Cost for Fuel Oil Burning — Producer Gas — Coke — Illuminating 
Gas — Disposal of Used Zinc or Zinc Residue. 

CHAPTER XXXII 

Galvanizing Specifications and Tests 291 

Specifications for Hot and Electro-Galvanizing — Preece or Copper 
Sulphate Test — Limitations of the Preece Test — Lead Acetate 
Test — Caustic Soda Test — The Preece Test — Manipulation and 
Temperature of the Preece Test — Consideration of Objections to 
Preece Test — Manipulation of Lead Acetate Test — Preece and 
Lead Acetate Tests Compared — Electrolytic Methods of Testing 
— Caustic Soda Test — Government Test — Salt Spray Test — Con- 
struction of Box for Salt Spray Test — Chart of Comparative 
Tests — Hydrochloric Acid and Antimony Chloride Tests for 
Sheots and Wire. 



Galvanizins and Tinning 



CHAPTER I 

Corrosion and Its Prevention 

1E0N and steel will invariably rust or corrode if exposed to 
the atmosphere without protection, and Mr, Alfred Sang, in 
The Iron Age, explains the reasons for this fact in an ex- 
cellent manner, as follows: 

"One of the most persistent problems which confront the 
worker in iron and steel is the prevention of corrosion. We can- 
not rid ourselves of the agents which effect the corrosion of iron 
without at the same time ridding ourselves of the agents which 
are essential to life itself. 

"Air is indispensable both to human respiration and for the for- 
mation of rust and other oxides, for which it supplies the oxy- 
gen; moisture is necessary for the formation of clouds, which 
make the earth fertile, and it also supplies the medium in which 
rusting takes place and hydrates the oxide; carbonic dioxide is 
an animal by-product and a raw material for the vegetable world, 
and the exchange of carbonic dioxide and oxygen, which is con- 
tinually taking place between the animal and the vegetable knig- 
dom, is of vital importance. Then, on the other hand, rust is not 
readily formed, if at all, unless there be an acid present, and the 
acid which is most universally distributed is carbonic acid, or 
hydrated carbonic dioxide. 

"There is, as you see, a close relationship between the processes 
of living and rusting, but, while human beings make up for the 
rusting or decaying of their tissues by nutrition, it has not yet 
been discovered how to feed or regenerate iron, and until such 
a discovery is made we are compelled to take our cue from the 
ancient Egyptians and resort to embalming. 

"There are two general ways of embalming iron to prevent 
its decomposition, which might be called, respectively, the metal- 
lic and non-metallic methods. In the non-metallic method the ar- 

9 



10 GALVANIZING AND TINNING 

tides are coated with, an organic substance, usually oil, or varnish, 
the efficiency of which depends on its being more or less airtight; 
when coloring matter is added to the oil it becomes a paint, but I 
understand from authorities on the subject that a varnish free 
from pigments is preferable to anything else. The metallic 
method consists of coating the iron with some other metal, and 
it is this method which I have come to discuss with you. 

"Iron rusts less easily than does steel; this is perhaps due to 
steel being a very composite material. In the iron, which forms 
the bulk of its composition, are dissolved or immersed a great 
variety of other substances; some of these are simple, such as 
graphite, silicon and manganese, and others are compound, such 
as carbides, sulfides, phosphides and silicides. The carbon com- 
pounds are very numerous and diversified, being due to different 
heat treatments; the best known are cementite, pearlite and mar- 
tensite. Just as variety is to some people the spice of living, so is 
heterogeneous composition the spice of rusting, in the present in- 
stance at any rate. jSTor is this by any means a solitary instance ; 
it is a well-known fact that chemically pure zinc is dissolved very 
slowly by certain acids, whereas the commercial product, especially 
if it be high in iron, is rapidly dissolved." 

Great trouble and expense annually falls upon manufacturers, 
metal workers and property o^vners through the rusting or cor- 
roding of iron and steel. An illustration of this is shown by the 
following, which recently appeared in The Iron Age: 

"The receivers of Milliken Brothers, Incorporated, 11 Broad- 
way, New York, have lately made some extensive experiments in 
connection with protecting from oxidation steel grillage beams 
used in building construction. More or less water is present in 
nearly every building where grillage beams are used. There- 
fore, unless the beams are absolutely protected, there will be oxi- 
dation. As such beams are not usually exposed to view and can- 
not be examined, if oxidation takes place after the building is up 
and the oxidation becomes serious, the security of the building is 
threatened. 

"Finding that coating the beams with paint, asphalt or tar 
cannot be absolutely relied on for a great length of time, Milli- 
ken Brothers have experimented with galvanizing by the hot 
process, after all the shop work has been done on the steel. It 
has been shown that concrete will adhere to galvanized steel 



CORROSION AND ITS PREVENTION 11 

beams as firmly as to iinpainted beams, and much better than to 
painted beams. Architects and engineers who have had occasion 
to examine galvanized Ashlar anchors and galvanized pipes used 
in connection with concrete have found that concrete will attach 
itself as readily to galvanized material as ungalvanized material. 
The advantage of galvanizing is that it gives the steel beam a 
complete zinc coating which will resist the a'ction of the water and 
therefore protect the steel. The expense connected with the gal- 
vanizing is considered small in comparison with the resulting 
benefits.'^ 

Zinc Coating the Best Rust Preventive 

It is my purpose in this volume to deal with the subject of coat- 
ing iron and steel products with zinc, or, as generally termed, gal- 
vanizing them (to prevent rusting), which has become a large and 
important industry in which much capital is invested and many 
men are employed. Zinc is without doubt the best protective coat- 
ing for iron and steel, and the reasons are clearly stated in The 
B7-ass World, which says: 

"It is difficult for many persons to understand why zinc is the 
best rust preventive for iron or steel, and they believe it is on ac- 
count of its cheapness that it is so extensively used. They have an 
idea that lead, being a cheaper metal, would answer far better, and 
as it is more non-corrosive than zinc, would protect the iron better. 
This is not a fact, however, as will subsequently be explained. 

"The very fact that zinc is a corrosive metal does not affect its 
properties when applied as a coating to iron or steel. Indeed, if it 
did not corrode, it would not be of value for such a purpose. When 
iron or steel, which has been coated with zinc, is exposed to the 
atmosphere, a galvanic action is set up, although, of course, ex- 
tremely slight. Any two dissimilar metals form a galvanic couple, 
but as zinc is the most electropositive metal, the galvanic action 
between the zinc and iron is as great as could be obtained when 
iron is used for one of the metals composing the couple. 

"The 1 esult is, therefore, that with the slight galvanic action set 
up on galvanized iron or steel, when exposed to the atmosphere, a 
corrosion takes place. Did it not follow, then there would be no 
protection. In this case, the zinc, being the electropositive metal, 
suffers corrosion at the expense of the electro-negative metal iron. 
The effect is that the corrosion goes on with the zinc exclusively 



12 GALVANIZING AND TINNING 

and iron is not corroded at all, provided any zinc is left on the 
iron or steel. This condition takes place whether a light or heavy 
coating of zinc is present. The only advantage of a heavy zinc 
coating is that it will last longer, but under ordinary atmospheric 
conditions, where a slight amount of moisture is the only exciting 
liquid, the galvanic action is very small and the zinc coating, be it 
ever so light, lasts a long time. In the case of sea-water or air 
saturated with salt moisture, the corrosion, of course, is much more 
rapid and a heavier zinc coating is required to resist it for a length 
of time. 

■^'The reason for the protection of iron or steel by a zinc coating 
is, therefore, on account of the fact that the zinc corrodes at the 
expense of the iron or steel by the galvanic action set up. Zinc, 
however, when exposed to the air, does not corrode rapidly or 
deeply and, in fact, very lightly. This property is of great value, 
as the zinc coating does not corrode rapidly, even with the galvanic 
action set up, so that it lasts for a far greater length of time than 
would naturally be expected. The very fact, however, that the zinc 
corrodes at the expense of the iron is all that is necessary to pro- 
tect the iron or steel, even though it be extremely slight. 

''^Other metals like lead or tin, on account of their not being 
electropositive to iron, do not act like zinc. They act simply as a 
covering like a paint or varnish, and if portions of the iron happen 
to be exposed, even such as a pinhole, the iron begins to corrode. 
AVith a zinc coating, however, this will not take place." 

Therefore there are well founded reasons for the growth and 
development of the galvanizing industry, since zinc is the best pro- 
tective coating for iron and steel and is comparatively low in 
price. 

The oldest galvanizing process and the one most generally used 
is the hot or dipping process, although the "cold" or Electro process 
is used to considerable extent and it has unquestionably gained 
ground since its invention, about twenty years ago. Sherardizing 
has come into use since the introduction of the Electro process. 
While its inventor does not use the term "galvanizing" in connec- 
tion with the Sherardizing process, it is, in fact, as truly a gal- 
vanizing process as is the hot dipping or Electro process. The 
protective coating in the Sherardizing process is metallic zinc de- 
posited from zinc dust or zinc oxide, while in the hot and Electro 
processes the zinc is used in the form of slabs or cast anodes. 



CORROSION AND ITS PREVENTION 13 

As the hot or dipping process is the oldest, we will give it our 
first attention, and writer will describe to the best of his ability 
methods employed in the different branches of the business, giving 
]-)rineipal attention to miscellaneous work, such as gray or malle- 
able iron castings, wi'ought iron and steel forgings, coal hods, and 
other articles made from sheet iron, devoting for obvious reasons 
short paragraphs to the galvanizing of sheets, pipe, wire, wire 
cloth and poultry netting. The galvanizing of these materials is 
simply one process in their manufacture ; and most of the concerns 
producing them either use methods of their own or patented de- 
vices, which it would be unfair on one hand, and useless on the 
other, to describe. Job shops for the handling of miscellaneous 
galvanizing are found in nearly all large cities in this country, and 
many manufacturers of specialties operate their own galvanizing 
plants. 

It may not be out of place to say that it has been, and still is, 
the practice of some engaged in this business to make as much of 
a mystery of the operations as possible. Mystery and secret for- 
mulae were looked upon (not so many years ago either) as the key 
to monopolizing many so-called metallurgical processes ; but those 
times have passed, and the reading public will have little trouble 
in following out any present methods if it will note the publica- 
tions and lucidly written books bearing on the subjects in ques- 
tion. One fallacy generally credited is that galvanizing kettles 
must never be allowed"to cool off. While it is true that it is not 
advisable to allow a kettle holding several tons of zinc to cool off 
at frequent intervals, and it is not in the interest of economy for 
one having a small amount of galvanizing to attempt to do it him- 
self, there is no reason why a kettle containing a few hundred 
pounds of metal cannot be operated fairly successfully, and pos- 
sibly to good advantage, if one is not conveniently located for 
sending the work to a jobbing galvanizer. We wish to impress the 
reader with the fact that we are not advocating the installation 
of a galvanizing plant as a matter of economy unless one has 
sufficient work to keep it in constant operation and employ skilled 
help. Unskilled workmen cannot produce best results, and the 
materials he must use are expensive. The operation of a very 
small plant will be found a costly experiment at the best, and 
should never be attempted unless actually necessary. 



CHAPTER II 
Hot Galvanizing Plant and Equipment 

TO THOSE contemplating the installation of a galvanizing 
plant the first consideration shonld be to isolate it as much 
as possible from the main factory, as the fumes arising 
from the chemicals used in the business are not only destructive 
to tools and machinery, but to many kinds of finished goods. It is 
very difficult to dispose of these fumes in such a way that they will 
not prove an annoyance as well as a menace to machmery, tools 
and stock. 

The Galvanizing Room 

In fitting up a room or building in which to locate the plant 
provision should be made to obtain the l)est possible ventilation. 
The building should be high posted, with a good ventilator in the 




Fig 2 — Front and Side Elevation of a Movable Hood 



roof, and better working conditions are obtained by covering the 
kettles and acid tanks with hoods connected to an exhaust fan of 
suitable size and speed. If an exhaust fan is used, most of the 
fumes arising from the kettles and acid tanks can be discharged 
into a stack or chimney of suitable height, and thus disposed of 
making conditions fairly comfortable. 

14 



HOT GALVANIZING PLANT AND EQUIPMENT 



15 



Where hoods are used over the kettles and tanks they should 
come as low as possible and not interfere with the workmen. They 
should be large enough to project well beyond the kettles or tanks 
so as to catch everything possible in the way of steam and smoke 
that naturally rises when the plant is in operation. When the 
work consists of castings and other small articles, there is no 
objection to having the hoods come to within 6 feet 6 inches of 
the floor. Where hoods are used on large kettles they should be 
suspended from a carriage or trolley on an overhead track which 
will permit of their being easily moved out of place when it is 
desirable to do so. We illustrate our method of putting up a 
movable hood by Fig. 2, although it is entirely possible that some- 
thing much better might be devised. 




Fig. 3 — Shop Akkangement with Tile Drains for Acid Tanks 



Considerable water is used in the hot process of galvanizing 
when miscellaneous work is done, and provision should be made 
to secure proper drainage. A good plan is to put catch basins 
under the various acid and water tanks, connected by tile pipe to 
sewer, as sho^vn in floor plan. Fig. 3. The floor can be cement 
or brick. 

If the work to be handled is gray iron it is not absolutely neces- 
sary to use steam, but if it is of a nature that requires the re- 
moval of scale, or if malleable castings are to be galvanized in 
quantities, steam should be brought into the room. 



16 



GALVANIZING AND TINNING 



A floor space 25 feet by 48 feet will accommodate an outfit 
such as we illustrate in Fig. 3. Much less floor space can be made 
to accommodate a very small plant that is designed to operate only 
at irregular intervals. 




Fig. 4 — Floor Plan of Galvanizing Room with Underground Flue 



Fig. 3 is the ground plan of a galvanizing plant, in which A is 
a tank for containing a solution of sulphuric acid and water for 
removing scale and rust; B is a water tank for storing work that 
has been cleaned; C is a tank for muriatic acid; D is a tank for 
hydrofluoric acid; E is the plate for drying the work before im- 
mersing it in the molten zinc; F is the kettle containing the 
molten zinc; G G are tanks, one of which is divided, and contain 



HOT GALVANIZING PLANT AND EQUIPMENT 17 

the water used for cooling the work after it has been removed 
from the galvanizing bath; H is an underground flue connecting 
the drying plate E with the chimney or stack J ; K is a pit giving 
access to the fire and ash pit under the drying plate E ; M M are 
catch basins, located under the several acid and water tanks, with 
tile pipe connections N to sewer. 

Another plan of a galvanizing plant is shown by Fig. 4. 

This plant, which occupies a floor of 25' x 50', was designed for 
use where the old-fashioned method of pickling sandy castings 
with sulphuric acid was to be employed. A small plant of this 
kind could be put in a much smaller floor space. In floor plan 
Fig. 4, A is a tank for containing a solution of sulphuric acid and 
water for removing scale and rust. B is a water tank for storing 
work that has been cleaned. C is a platform where castings are 
placed to free them from sand with the use of sulphuric acid. D is 
a tank used to contain the solution for removing the sand from 
the castings after they have been placed on the platform. E is a 
tank for containing muriatic acid. F is the plate for drying the 
work before immersing it in the molten metal. G is the kettle 
containing the metal, and H is the tank used for cooling the work 
after it is coated with the zinc. I I indicate the loose planks 
covering the ash pits, shown in Fig. 11 as P P. K is an under- 
ground flue connecting the drying plate F with the chimney or 
stack L; and M is a pit to give access to the ash pit under the 
drying plate F. 

The Equipment 

The equipment of a galvanizing plant for miscellaneous work 
consists of a kettle of suitable size, which should be built of the 
very best material obtainable; a drying "arch," ''plate" or "oven" 
for drying the castings prior to immersing them in the molten 
zinc; wooden tanks for containing water and the different acid 
solutions; and miscellaneous tools best adapted to the work in 
hand, such as tongs, hooks and baskets of perforated sheet iron or 
wire cloth. Considerable ingenuity can be exercised in devising 
implements for handling the various kinds of work. We shall 
refer to this matter of tools later under a special head. 

The material used in the construction of galvanizing kettles and 
tools which come in contact with the molten spelter is a matter of 
great importance. In this connection, the statement of the super- 



18 GALVANIZING AND TINNING 

intendent of one of the largest sheet galvanizing plants in the 
country is interesting, and we give it herewith. 

The endeavor to find the most suitable material for manu- 
facturing those parts of the machinery which are immersed in 
spelter, as well as the best container for the molten spelter, has 
occupied the attention of galvanizers for all time. The only sub- 
stances which are not dissolved are vitreous, and consequently, im- 
practical. All of the common metals are soluble in molten zinc, 
and all of them are miscible in all porportions, with the exception 
of lead and iron. For this reason, and because of the many other 
desirable properties which iron possesses, it is universally used at 
the present time. 

The old galvanizers made their machinery of wrought iron; 
but with the introduction of Bessemer and open hearth steel have 
quite generally adopted this material, because it possesses certain 
very distinct advantages over wrought iron. It does, however, go 
into solution much more rapidly than the old wrought iron did; 
so that for the last ten years the search has been for a material 
which will work as well as steel does, and resist the solvent action 
as well as the iron. 

The laws of physics teach us that an impure substance will go 
into solution more rapidly than a pure one, and we do not find 
exceptions when dissolving iron in zinc. The purer the iron the 
more slowly it goes into solution. This is the reason that the 
old-fashioned puddled iron lasted so much longer than the modern 
steel. Now that ingot iron is being commercially produced, it has 
been very easy to demonstrate this fact in a scientific manner. 

In a recent investigation the following facts were disclosed: 
Sixteen gauge samples of various analysis were suspended in molten 
spelter for twelve days with the following results: 

Sulphur 

Phosphorus 

Carbon 

Manganese 

Silicon 

Copper 

Loss in 12 

Having satisfactorily demonstrated that there was a very marked 
difference between pure iron and steel (impure iron), another set 



Armco Iron 


Steel 


Steel 


.032 


.036 


.022 


.008 


.067 


.006 


.010 


.045 


.010 


.017 


.372 


.145 


trace 


trace 


trace 


.048 


trace 


.192 


11.2% 


40.9% 


27.00% 



HOT GALVANIZING PLANT AND EQUIPMENT 19 

of experiments was conducted to bring out the difference in the 
effect between slight variations in very pure iron. Samples of the 
following analysis were used, and were suspended for four hun- 
dred fifty hours (three 150 hour periods). 





1 


2 


3 


4 


5 


Silicon 


trace 


trace 


trace 


trace 


trace 


Sulphur 


.022 


.025 


.025 


.026 


.027 


Phosphorus 


.003 


.004 


.003 


.003 


.005 


Carbon 


.015 


.04 


.015 


.01 


.10 


Manganese 


.02 


.005 


.04 


.01 


.065 


Copper 


.045 


.035 


.11 


.11 




Oxygen 


.015 


.017 


.025 


.041 


.03 


Total Impurity 


.120 


.126 


.218 


.200 


.227 


Iron by difl'erence 


99.88 


99.874 


99.782 


99.80 


99.773 


Loss in 450 hours 


34.4% 


38.5% 


42.0% 


55.7% 


(41.5% loss in 
300 hours.) 


Average weight of coi 


iting in 150 hours 


370 314 272 


248 212 



It will be noticed that the rate of solution increases directly in 
proportion to the amount of impurit3^ These specimens were all 
weighed very carefully, were totally immersed in spelter, not com- 
ing in contact with the salammoniac flux at any time ; the coating 
being stripped off with sodium hydroxide, which dissolves the 
spelter but does not attack the iron. From these results it is evi- 
dent that while dealing with commercially pure iron it is essential 
to secure the very purest. A material containing 99.84% iron 
being much better than one containing only 99.75% iron. You 
will note also that the rate of solution increases with the 
amount of oxygen; showing the additional necessity of securing a 
thoroughly degassified and deoxidized material. 

Another interesting fact to be noticed in the table given above 
is that the weight of coating taken on varies inversely as the rate of 
solution; that is, the more rapidly the material dissolves, the 
lighter coating it takes on. 

These facts as worked out in the laboratory are very interest- 
ing, but needed verification in actual practice before they could 
be of any real importance to the galvanizer. For this reason, all 
parts of the galvanizing machine under the spelter, in one manu- 
facturer's plant, were manufactured of Armco Iron. He finds that 
cast Armco Iron lasts just about as long as rolled or forged 10 
carbon steel; whereas Armco Iron, properly worked and heat 



20 GALVANIZING AND TINNING 

treated, will last from three to seven times as long as mild steel 
will. Flux boxes, for example, lasting from eight to ten months. 

These statements are borne out and given additional weight by 
a comparison of galvanized Armco Iron sheets with galvanized 
mild open hearth steel sheets. The iron content of a clean spelter 
bath is approximately .02%. Any iron in excess of this forming 
dross, and settling to the bottom. The coating on Armco Iron 
sheets contains about 3% iron, while the coating on steel sheets 
contains about 4% ; showing very definitely that even in the short 
time that the sheets are in the spelter bath, steel goes into solution 
much more rapidly. 

It is a source of great satisfaction to know that a material is 
being commercially produced, which lasts even longer in the 
spelter than the old-fashioned wrought iron, and at the same time 
possesses all the excellent working qualities of steel. 

The Selection of a Kettle 

In deciding what size kettle to install one must be guided by the 
nature and quantity of work to be done. If small articles are to 
be handled, and the quantity is such as to require the plant to be 
operated only at intervals, a kettle 8 feet long, 15 or 18 inches 
wide and 20 inches deep will answer every purpose, but it is ex- 
tremely difficult to keep an even temperature of the metal in a 
kettle of this size. The only excuse for using such a small kettle 
is for doing an extremely limited amount of work as a matter of 
convenience, with cost as a secondary consideration. 

Bricking in a Galvanizing Kettle 

There are several methods of heating galvanizing kettles. Some 
are heated with soft coal, some with fuel oil and some with natural 
gas. The fuel most commonly used, however, is coke. For this 
reason we shall show, by illustrations, three methods of bricking 
in coke-fired kettles. We do not attempt to describe any particu- 
lar method of oil or natural gas heating, as concerns using either 
fuel usually have their own methods of application. 

Figs. 5, 6 and 7 show methods of setting a small kettle not 
deep enough to require ash pits at the sides and not designed to be 
operated continually. The grates F F are bars of iron that may 
be withdrawn when it is desired to let the fires out, and replaced 
when required for use. Fig. 5 is a top plan of the brick work and 



HOT GALVANIZING PLANT AND EQUIPMENT 21 

kettle. Fi'j;. (i is a Ncrlical cross section of Fig. 5 at A A, aud 
Fiff. 7 is a horizontal section oi" Fig. G at B B. 



«Ioj 



^-t-. 



D 



—— a.-. 
li 






t: 



Fig. 5- 



eff 




'bjy^, 



-PLA^^ OF Kettle 



Fig. 7- 



Secf/'on B-B 

-Arrangement at Grate Line 




Section A- A 

Fig. 6 — Vertical Cross Section of Furnace and Kettle 

Fig. 8 shows the casting details for setting kettle as sho^vn in 
Figs. 5, 6 and 7. D is a plate to cover top of brick work surround- 
ing the kettle, and its position is designated in Fig. 5 as D D. 
E is a casting used on outside of brick work on both sides of kettle 
and in connection with bolts passing through their ends serve to 
bind the brick work together. Their position is designated in 
Fig. 6 as E E. F is a grate bar, the position of which is shown 
in Fig. 7 at F F, and G G are the castings for supporting each 
end of the grate bars F. Their position is designated as G G in 
Figs. 6 and 7. The castings for the upper and lower draft hole 
casings with doors, designated as H and I in Figs. 5 and 6, can 
be made the same as castings K, L, M and N in Fig. 13. 



22 



(GALVANIZING AND TINNING 



^ <^ 



B O 



Fig. 8 — Casting Details for Setting Kettle 



if 



r^ 1 



r-r~i r-r-L 



Qu 



-Vl 



/^ 



^^^^^^^^^■»" 






O -A 



■=i=r 



^^W^ 



q_j Li__|-Hr 



FiG. 9 — Top Plan of Brickwork for Larger Kettle 



lax 



^, I . I , I . I . I . I . I . I . T^A^" 




Fig. 10 — Side Elevation of the Same Kettle 



HOT GALVANIZING PLANT AND EQUIPMENT 



23 



Figs. 9, 10, 11 and 12 show manner of setting larger kettles 
where grates are used ; Pig. 9 being a top plan of the brick work ; 
Fig. 10 a side elevation; Fig. 11 a vertical section at A A; Fig. 9 
and Fig. 12 a horizontal section at the grate line. 






Fig. 11 — Vertical Cross Section of Kettle and Furnace 




Fig. 12 — Horizontal Section at the Grate Line 

Fig. 13 gives details of all castings necessary for setting all 
grate-fired kettles, as shown in Figs. 9, 10, 11 and 12. A, Fig. 13, 
is a coping plate, the position of which is shown in Figs. 9, 10 
and 11 as A A. These plates, when held in place by the bolts C, 
serve to prevent the sides of the kettle from springing outward 
when the iron blocks D, Fig. 13, are in their place, as shown in 



24 



GALVANIZING AND TINNING 



Figs. 9 and 11. Coping plates for kettles 4 to G ft. long should be 
2 finches thick and 10 inches wide. The fire spaces E E in Figs. 9 
and 1 1 should not be more than 7 inches wide, and the same length 
as the inside of the kettle. F in Fig. l3 is an iron plate 1 inch thick, 
and the position of these plates on the brick work is shown as 
F F in Figs. 9 and 11. Gr in Fig. 13 is a section of grate, the 
position of which is designated G G in Figs. 11 and 12. The 
openings of these grates should be about 1 inch wide, and the 





A 




1 1 1 

1 II 




ii i*^^ 



^^p^ 



^=^ 



3 



M 



3 




D 



Fig. 13 — Details of Castings lcr Siottixg G::ate-Fired Kettle 



grates should be wide enough to span the fire spaces E E in Figs. 9 
and 11 and rest on plates 11 tl and the pier I on which the kettle 
B rests, as shown in Fig. 11. Plates like H in Fig. 13 are used 
to rest the outer edge of the grates G G on, as shown in Figs. 11 
and 12, and also to help support the brick walls on each side of 
the kettle. Plates such as H in Fig. 13 may also be used to cover 
the top of fire boxes E E in Figs. 9 and 11, and should be about 
% inch thick and 12 inches wide; their length to be determined by 
the length of the kettle. K in Fig. 13 is a cast iron casing for the 



HOT GALVANIZING PLANT AND EQUIPMENT 



25 



upper draft holes, indicated as K K in Figs. 10 and 11. These 
casings should be about 10 inches long with openings about 4 by 
4 inches. They should also be arranged to close with sliding doors 
L, as shown at L, Fig. 10. M in Fig. 13 shows a cast iron casing 
for the lower set of draft holes in which the openings should be 
about 8 by 13 inches. Th^ir position in the brick work is desig- 
nated M in Figs. 10, 11 and 12. N in Fig. 13 is a sliding door 
for the draft hole casings M, and they are designated N in Figs. 
10 and 11. in Fig. 13 is a cast iron foundation washer which 
is built in the brick work on the bottom ends of the vertical 
bolts C. The ash pits P P, Fig. 11, should be about 2 feet wide 
and covered with loose floor planks so that easy access may be had 
to the ash pits for the purpose of opening or closing the lower 






Fig. 14 — Plan and Elevations of Kettle 



drafts, and also for removing the ashes from the spaces R R under 
the grates G G-. Fig. 12 shows the grates G Gr in position, and 
also the manner of laying the bricks between the draft casings M M. 
I indicates the pier on which the kettle rests. It will be seen that 
the brick work between the lower draft casings M M is built in a 
way which will allow all possible access to the grates G G from the 
ash pits P P. The walls along each side of the kettle should have 
a lining of fire brick extending from the grates upward to the 
coping plates A A, as shown in Fig. 11. 

Fig. 14 shows a kettle ni which the body is formed of one piece, 
with rivets placed where the fire will not affect them. While a 
kettle for general use built after this illustration is our preference 
for many reasons, it does not follow that the work could not be 
done in a kettle of some other shape. 



26 



GALVANIZING AND TINNING 



Figs. 15, 16 and 17 show the setting of kettles fired without 
grates and with only one set of draft holes. Fig. 15 is a sectional 




Fig. 15 — Section^ of Brickwork and KLettle at A A, Fig. 17 

plan of the hrick work and kettle through 17 at A A. Fig. 16 is a 
sectional side elevation through Fig. 15 at B B. Fig. 17 is a sec- 
tional end elevation through Fig. 15 at C C. 







.'<2k; k Ci. *. ^' * 



n// <-^ ,„i J) 



Fig. 16 — Side Elevatiojn at B B, Fig. 15 



Figs. 18 to 23 show construction of a simple and effective ar- 
rangement for drying eastings previous to dipping them in the 
molten zinc. Fig. 18 is a side elevation of a "drier" showing 



HOT GALVANIZING PLANT AND EQUIPMENT 



27 



furnace front with fire and ash pit doors. Fig. 19 is a longitudinal 
section of Fiar. 22 at C C. Fig. 20 is a lateral section of Fig. 22 




Fig. 17 — Section at C C, Fig. 15 



J l IL 



Jl IL 



1\ \L 



1 1 II IJ 



J \ I E 



n i \ r 



3 







Fig. 18 — General View of Furnace for Drying Castings 

at A A. Fig. 21 is a lateral section of Fig. 22 through B B, 
ghowing ash pits and grates. Fig. 22 is a longitudinal section of 



28 



GALVANIZING AND TINNING 



Fig. 21 through D D, and shows arrangements of flues. Fig. 23 is 
a longitudinal section of Fig. 21 through E E, and shows grate 
and fire box with fire brick lining. 

We give the method of setting kettles with and without grates 
for the reason that there is a diversity of opinion as to which is 




Secffon C-C 






Fig. 19 — Loivgitudijval Sectiotv" at C C, Fig. 22 




::iO- 



M^M^IMIMWW^M^^M: 



Fig. 20- 



Sscf/on /^-/t 
-Cross Section at A A. Fig. 22, Showing Flues 



the better method. Without discussing this matter pro or con, the 
author will simply say that he prefers a kettle fired without grates. 
Some claim that a grate fired kettle lasts much longer than one 



HOT GALVANIZING PLANT AND EQUIPMENT 



29 




4^^ p^' ^.4~f. 






Sect/on s-3 

Fig. 21 — Vertical Section Through B B, Fig. 22, Showixg Furnace 

AND Flues 
A ^ 




Sec-r/or> O-o 



Fig. 22 — Plan of Drier, Showing Top Flues at D D, Fig. 21 



30 



GALVANIZING AND TINNING 



set without grates, as without grates the draft comes directly onto 
the side of the kettle, which results in burning it out much quicker 
than would otherwise be the case. 




Secr/on £-£■ 



Fig. 23 — Plan Showing Guate and Fire Box at E E, Fig. 21 



Tanks for Acid Solutions and Water 

In our opinion, the best lumber for acid tanks is cypress, al- 
though some prefer the different varieties of pine. Most galvaniz- 
ers use wooden tanks for containing the cooling and rinsing waters. 
Water tanks made of boiler iron will give very good service, in 
fact they are more economical than wooden water tanks. Wooden 
tanks for holding the various acid solutions should invariably be 
put together with copper bolts, nuts and washers, and it is a good 
plan to line the inside of such tanks with rough boards that can 
be replaced when worn orut. These linings protect the inside of 
the tanks and will increase their life very materially. It will be 
found a good plan to coat the inside of wooden tanks intended for 
cold acid with asphaltum. The asphaltum should be heated as 



HOT GALVANIZING PLANT AND EQUIPMENT 



31 



hot as possible without danger of its catching fire and put on 
thickly with an old broom. When asphaltum is used in this way 
it is absolutely necessary to protect it with a rough board lining 
such as mentioned above. 

It was formerly considered necessary to line acid tanks with 
sheet lead, but of late years this is rarely done, as the use of lead 
linings makes the maintenance of acid tanks a very serious item 
of expense. If the tanks are properly constructed there is no 
necessity for lining with lead. 



^^.^^^^^^:>^^^^^^^^^=;;^^^ 











<<Ss^'m 


m 


^^^^ 





Fig. 24 — Plan ais^d Elevations of Acid Tank 

Fig. 24 shows a good method for constructing wooden tanks. 
It is unnecessary to build expensive tanks for a small plant that 
is only to be run at irregular intervals. Oil barrels sawed in half, 
thoroughly cleaned, answer every purpose, provided, of course, the 
work is of a size which half l)arrels will accommodate. In build- 
ing acid tanks one must be guided entirely by requirements in 
determining size. 



Tools for Galvanizing 

The tools employed in galvanizing usually consist of tongs of 
various shapes and sizes, dependent entirely on the shape of the 
articles to be handled. Perforated baskets of sheet iron for gal- 
vanizing small articles, and baskets made from heavy wire cloth 
can be used to good advantage for a great many purposes, as can 
wires bent in various shapes. As already suggested under a previ- 



32 GALVANIZING AND TINNING 

ous heading, a great deal of ingenuity may be exercised in con- 
structing special tools for the handling of work of various shapes. 
In Fig. 25 we show a few of the most common implements that 
serve as tools for the handling of a variety of work. A shows a 
basket made of wire cloth, attached to an iron handle of suitable 
length, preferably from 3| to 4 feet. B is a perforated basket 




Fig. 25 — Tools Used in Galvanizing 

made of sheet iron. This tool is necessary for dipping small ar- 
ticles, such as nails, tacks, screws and many other articles too small 
to be handled otherwise. Several of the baskets, A and B, should 
be provided for use when wanted. C is a tool made of common 
round iron bent in the form of a letter U. This tool is useful for 
immersing in the molten metal articles too large to be immersed 
in baskets. D is also used for dipping small articles that can be 
handled in this way better than in baskets. D is made of wire of 
suitable size, and it is a good plan to have at least a dozen each 
of C and D for use when required. E and F are skimmers. The 
bowl of F is made of No. 16 or No. 18 gauge sheet iron and 
perforated with r^ inch holes. It should be provided with a handle 
at least 4 feet in length, and the bowl should be about 8 inches in 
diameter. The blade of E should be made of a piece of No. 16 



HOT GALVANIZING PLANT AND EQUIPMENT 33 

gauge sheet iron from i to 6 inches in length by 2 inches in width. 
The handle should be made of § or ^ inch round iron, from 15 to 
18 inches in length. G is a tool used for suspending castings in 
the galvanizing bath that are strung on wires. It should be made 
of f or ^ inch round iron, and l)e from 4^ to 5 feet in length, 
11 is a scoop for removing dross from the galvanizing kettle. The 
use of all these tools will be referred to in describing the different 
operations of galvanizing. 



CHAPTER III 

The Pyrometer 

THE author has had many inquiries regarding the use of a 
pyrometer in a galvanizing kettle. While it has not been his 
practice, or generally the practice of other galvanizers, to 
depend on the pyrometer to any great extent, preferring that the 
operator should school himself to determine the proper heat of the 
metal by observation, the introduction of improved instruments for 
determining more accurately actual temperatures is undoubtedly 
making converts to new and better methods. 

While a reliable pyrometer is without question an advantage to 
the hot galvanizer, it can never replace the skilled operator. The 
reason is obvious. In the first place, hardly any two brands of 
spelter will give the same results at the same temperature. Then 
again, different classes of work require widely different tempera- 
tures of the galvanizing bath. If gray iron castings were to be 
galvanized a temperature proper for some other classes of work 
would be found altogether too high. Where a kettle is used for 
miscellaneous work it is necessary to change the temperature of 
the metal several times a day. In such cases I have found a 
pyrometer of very little use. A pyrometer is an advantage on 
straight work, such as sheets, wire cloth, etc., etc., or, in fact, any 
class of work that is run continuously day after day. A good 
pyrometer placed in the kettle from time to time is of great as- 
sistance to the operator, however skilful he may be, and it is also 
of great advantage in caring for the kettle at night and at other 
times when not in operation. 

When the ordinary style of pyrometer is used the stem should 
be protected from the action of the zinc or it will soon be de- 
stroyed. A means by which the stem of the pyrometer is kept 
from contact with the molten zinc, at the same time giving the 
same result as if in actual contact, is shown in detail by Fig. 27. 
The arrangement consists of a piece of 2-inch pipe about 20 inches 
long with one end tightly closed. The top of the pipe is provided 
with a bushing having a hole a little larger in diameter than the 

34 



THE PYROMETER 35 

stem of the pyrometer. A similar bushing is placed in the pipe 
about 3 inches from the bottom and the two serve to keep the 
pyrometer in an upright position. The pipe surrounding the stem 
of the pyrometer is filled with lead so that when the apparatus is 
placed in the kettle there is a direct metallic connection between 
the stem of the pyrometer and the molten zinc. Fig. 26 shows 
such a pyrometer in position in the kettle. 




Fig. 26 — Correct Position of Pyrometer in Furnace 

The importance of maintaining a safety point in the temperature 
of the hot galvanizing bath is recognized by everyone, and the ques- 
tion has received the attention of practical and scientific men. A 
paper presented before the Mechanical Section of the Engineers' 
Society of Western Pennsylvania in 1912, by S. H. Stupakoff of 
Pittsburgh, puts this matter so concisely and intelligently that I 
have asked and received the permission of the gentleman to use 
the paper in the production of this book. Mr. Stupakoff says as 
follows : 

Considerable difficulty is encountered in galvanizing practice to 
keep the temperature of the molten metal within the limits which 
produce a clean and uniform coating on the surface of articles 
treated by this process. The most suitable galvanizing tempera- 
ture lies usually about 50 deg. Fahr. above the melting point of the 
metal bath. Ten or fifteen degrees either way may result in in- 
ferior products. The melting point of pure zinc is 787 deg. Fahr. 
Impurities or other metals, such as lead, antimony, aluminum, etc., 



36 



GALVANIZING AND TINNING 



intentionally added, or accidentally occurring in the mixture, usu- 
ally lower the melting point; and in such a case it will be found 
preferable to lower the galvanizing temperature accordingly. This 
makes us conclude that the temperatures of galvanizing baths re- 
quire close watching. Ten degrees above or below 850 deg. Fahr. 
is very little ; it would escape the notice of the best of us, unless we 




27 — Device for Protecting Pyrometer 



were guided by the most reliable instruments. It lies beyond the 
region of the human senses. We may be able to distinguish a 
difference of 10 or 15 deg. above or below 65 deg. Fahr. when 
sitting quietly at our studies, feeling uncomfortably cold at 50 
or 55 deg. or uncomfortably warm at 75 or 80 deg., but that is 
about our limit. 

This would indicate that our metals are far more sensitive to 
small variations of temperature than the human body. And more 
so, if we consider that 10 deg. difference at 65 represents about 
15 1/3 per cent., whereas 10 deg. at 850 is less than 1 1/5 of 1 
per cent. Unaided by trustwortliy temperature measuring instru- 
ments it will always remain an extremely difficult matter, even 
for an expert, to make an approximate estimate of conditions. 
Though it is conceded that the phenomena invariably accompany- 
ing changes of temperature, if intelligently interpreted, may lead 



TIIF. PYROMETER 37 

to a successful conclusion of metallurgical processes, it cannot be 
denied that whatever they may involve they depend upon the per- 
sonal equation, which cannot be tolerated in modern manufacturing 
practice. 

We receive in this manner undisputable indications of the condi- 
tions of the fluid metal in galvanizing j^ractice through the forma- 
tion of dross, the degree of intensity of its coloring, the behavior 
of the flux, the intricate motions on the skimmed, clean surface 
of the metal accompanied by the appearance of variously shaped 
crystals, like ice crystals on a window pane, and most of all through 
the appearance of the metallic coating of the galvanized products 
themselves. 

They may remain forever an enigma to the uninitiated, whereas 
a man who has spent a lifetime at this task may have finally mas- 
tered the problem. Nevertheless it is not a rare occurrence that 
a galvanizing tank in the hands of an expert operator gives out 
after a few months ; and replacing it is always a very costly mat- 
ter. The cause in ninety-nine cases in a hundred is overheating 
the metal. 

As it is very important that a constant temjDerature be main- 
tained in the bath, reliable instruments should be provided that will 
indicate the temperature correctly. This is far more difficult than 
ordinarily assumed. It may be appreciated to some extent if the 
assertion of a friend, who has had wide experience in this direction, 
be accepted as descriptive of the average general conditions in 
recent galvanizing practice. He assured me that he had tried many 
heat measuring instruments during the last twenty years, and that 
not one had given satisfaction. Some failed because they were 
too fragile, others because they were unrelial^le from the beginning, 
some because they were inconstant and changing in time, and still 
others because they were erratic in their indications. The last of 
these, which undoubtedly embraces the majority of instruments 
of the kind, is the least tolerable of the lot. Instead of imparting 
confidence, they give just cause to distrust, and they invite ridicule 
of the workingmen to whom they are represented as infallible. I 
have often run against freaks of this kind. Few of them would 
indicate the correct temperature within 50 or 100 deg. Some would 
run along smoothly for a while, and then drop 300 or 400 degrees 
within a half or three-quarters of an hour and rising again as 
quickly. Judging from the series of lassitudes and occasional 



38 GALVANIZING AND TINNING 

sudden spurts of activity, they represented anything but existing 
conditions. Now, what faith could a man have in such an erratic 
indicating device, if he knows that a tank containing from 10 to 
15 tons of molten zinc will not cool more than 19 or 20 deg. Fahr. 
per hour with all the fires turned. ofE? Let me give an example 
taken from actual practice. 

The temperature of a galvanizing tank, containing about 240,000 
lbs. of zinc, dropped 170 deg., from 850 to 680 deg. Fahr. in 27 
hours, after the gas fires were shut off. This would indicate an 
average cooling of only six degrees and a fraction per hour, which 
is less than a third of the maximum drop that has just been 
mentioned. 

Melting point of zinc (M. P.) 419.5° C. 

Specific heat of liquid zinc (S) 0.1275 

Mean specific heat of solid zinc (from o° to 

t°) (S.M.) 0.0906 + 0.000044t 

Mean specific heat before fusion at M. P 0.109058 

Heat in solid metal at M. P. (from above) 45.75 Calories 

Heat in solid metal at M. P. (Eichards) 45.20 Calories 

Heat in liquid metal at M. P. (Person) 67.80 Calories 

Latent heat of fusion (observed) 22.60 Calories 

Latent heat of fusion (by 2.1 T rale) 22.40 Calories 

Latent heat of fusion (from above) 22.05 Calories 

Galvanizing temperature (about) 455° C 

Heat required to raise liquid metal from M. P. to 

455° C 4.5 Calories 

Total heat in liquid metal at 455° C 72.3 Calories 

Total heat in liquid metal at 455° C 130.14 B. t. u. 

The latent heat of fusion of zinc per pound (Cal.) 22.6 

Heat in molten metal at 850 deg. Fahr. is (Cal.) 72.26 

and at 680 deg., to which it had been cooled (Cal.) 38.28 

hence it has parted at 680 deg. with (Cal.) 33.94 

Distributed over the 27 hours, cooling, this is about ll^ cal. 
per lb. hr. for the whole mass of 24,000 lb. is about 

(CaL per lb. hr.) 300000 

Deducting from the above (Cal.) 33.94 

The latent heat (CaL) 22.6 

there remains almost exactly 1/3 (Cal.) 11.34 

which should be evenly distributed over 9 hours, which is 
1/3 of the total time of cooling ; the remaining 2/3, or 18 
hours, were consumed to turn the liquid metal into a solid 
mass. Dividing 170, the total drop in temperature by 9, 
the time in hours, we find 19, or, say, roundly 20 deg. 
Fahr, drop per hour. 



• THE PYROMETER 39 

The freezing of tlic metal should have commenced accord- 
ingly, after (hours ) 3 

it would have been solid throughout after (hours) 21 

and tlie temperature would have dropped during the (hours) . . .6 
remaining, at a fairly even rate per hour of (deg. Fahr.) . . .20 

.This is a rough illustration of what takes place in practice. The 
finer shades of variations have been purposely omitted in this cal- 
culation to save complications. The observations cited were made 
during the winter months; the thermometer indicating about 30 
or 35 deg. Fahr. Changes in atmospheric conditions would cause 
considerable change in the results, as the heat lost by the molten 
metal is given up to the surrounding air principally by conduction 
and convection. Diiferences in temperature and movement, draft, 
of the air would be the most important factors in such changes. 

The question is often asked whether reliable test thermometers 
can be obtained for the purpose. Undoubtedly they are to be had, 
but there should be no occasion to use them for checking other in- 
struments of their kind, if such convenient and relial)le means can 
be used as the freezing point of the metal itself. "We have no reason 
to find fault with our commercial thermometers. The better grade 
can be relied upon to be correct within one-half of a division, even 
without a certificate; but most confusing results can be obtained 
with a thermometer, especially with a long stem thermometer, if 
it is not correctly used. Ordinary commercial thermometers are 
graduated to be used ^t full immersion ; that is, not only the bulb, 
but also the entire mercury column is to be exposed to the tempera- 
ture which is to be measured. However, full immersion is a con- 
dition seldom met with when a thermometer is used for technical 
purposes. In most instances only a portion of the stem can be 
immersed into the heated medium, and unless the thermometer has 
been especially constructed for the purpose, grave errors will result. 
Otto Bechstein says in his description of "Instruments for the meas- 
uring of temperatures in technical pursuits" that this error may 
amount to 50 deg. Cent., and more in long-stem thermometers. I 
must confess that this is more than I have ever had occasion to 
observe ; but, notwithstanding this, he may be right. As ridiculous 
as it may seem, it appears, therefore, quite appropriate to recom- 
mend to users that they learn the proper use of a thermometer, and, 
furthermore, when purchasing to fully describe the requirements. 
It would seem that, if such apparently simple devices as Indus- 



40 GALVANIZING AND TINNING 

trial thermometers require the amount of care in their construction 
and application as has here been described, other types of heat- 
measuring instruments, which command more extended ranges and 
which see a more severe use, can scarcely be expected to be entirely 
free from objectionable features. Each type has its scope, each 
must be used with due care and with each set rules must be intelli- 
gently observed to obtain satisfactory results in their application. 

The most important features of some of them have been referred 
to; it was impossible to enter into the details of all the instru- 
ments, nor could all their useful application in the large number 
of processes of the metal industries be described at length in a 
paper of necessarily limited length. To cover the entire ground 
would fill a large volume and require a series of lectures. The 
discussion of the subject may bring forth many points of interest 
which have not been mentioned. 



CHAPTER IV 

Materials Used in Hot Galvanizing 

TTTE materials used in galvanizing are slab zinc (spelter), 
pig lead, white and gray granulated sal ammoniac, zinc 
ammonium chloride, muriatic, sulphuric and hydrofluoric 
acids, coke (if side fired kettles are used), oil, glycerine, and 
aluminum properly mixed for fluxing metal. 

Spelter 

We cannot, with fairness, express a preference for any particular 
brand of spelter; but on general principles we do recommend the 
use of Virgin spelter smelted by a reliable Arm. We do not recom- 
mend the use of what is commercially known as "Eemelt" spelter 
by those who are not familiar with this metal. While most Re- 
melt spelter is run down from sheet zinc, there are several brands 
on the market which have been recovered from zinc dross by those 
who have not the facilities for properly doing the work. We do 
not wish to go on record as claiming it impossible to recover good 
metal from zinc dross. In fact, we have in mind a brand of spelter 
that is recovered from zinc dross which gives as good results, both 
in quality of the work and economy, as the best brands of Virgin 
spelter. Great progress has been made in the last few years toward 
the recovery of galvanizing by-products of all kinds, and materials 
at one time considered worthless and consigned to the waste heap 
are now valuable. 

No infallible rule by which the layman may determine the 
quality of spelter can be given. The only positive way is by an- 
alysis. In a general way the quality of spelter may be determined 
fairly well by breaking slabs and observing the fracture. If the 
fracture shows a bright, regular and large granular face it indi- 
cates that the spelter is of good quality, but if the fracture shows 
dark, small granules it indicates quality that is not the best. A 
magnifying glass, when applied to a freshly broken slab of Eemelt 
spelter, will often reveal small black particles acting as wedges be- 
tween the granules. These particles are foreign matter prin- 
cipally, and therefore lessen the value of the spelter as well as 

41 



42 GALVANIZING AND TINNING 

acting as a detriment in melting and coating operations. How- 
ever, if the policy of bujang only Prime Western or Virgin spelter 
is followed, one can be snre that no dross is introduced into the 
galvanizing liath in the spelter, as would be the case if Eemelt 
spelter, reclaimed by crude methods from zinc dross, was used. 

Lead 

Scrap lead will answer every piirpose for use in the galvanizing 
kettle as described under the heading "Filling a New Kettle," 
but if it is necessary to procure pig lead for this purpose it is best 
to buy what is known as "hard lead/^ 

White and Gray Granulated Sal Ammoniac 

These chemicals play an important part in the process of hot 
galvanizing; the grade known as "gray granulated" sal ammoniac 
being used to form a flux on the surface of the zinc, which flux is 
necessary to facilitate the proper coating of the work and to re- 
tard the oxidation of the molten zinc by excluding the air. White 
sal ammoniac is used to sprinkle on the surface of the molten metal 
as the work is withdrawn. Some galvanizers use the white for 
both purposes. These chemicals are an important item of expense 
in the cost of hot galvanizing and care should be exercised against 
buying inferior grades. The best sources of supply can only be 
learned by experience, as it would be manifestly out of place for 
the author to express a preference in this book for the product of 
any particular manufacturer located either in this country or 
abroad. 

Zinc Ammonium Chloride 

The use of zinc ammonium chloride on the galvanizing bath 
as a substitute for gray granulated sal ammoniac is comparatively 
a new idea. As a matter of fact, it is only used at this writing 
by comparatively few galvanizers. We give it the preference over 
gray granulated sal ammoniac, not by reason of economy, but from 
the standpoint of comfort. The fumes of zinc ammonium chloride 
rising from the surface of the molten zinc are less disagreeable to 
the operator and less destructive than the fumes of sal ammoniac, 
and, in our opinion, it gives much better results than the sal 
ammoniac. 



MATERIALS USED IN HOT GALVANIZING 43 

Muriatic, Sulphuric and Hydrofluoric Acids 

These acids are readily oljtainablc in all important trade centers 
and are so common that no extended reference regarding tliem is 
necessary. 

Coke 

Coke is the only practicable fuel that can be used on kettles of 
the character shown in the preceding pages. While it is possible 
to use what is known as foundry coke for heating a galvanizing 
kettle, it is unsatisfactory, and the best results are obtained with 
that produced in makhig illuminating gas, commonly known as 
gas coke, which may usually be purchased at a lower figure. 

Oil 

Oil is commonly used in the galvanizing process on the surface 
of the water in which the work is cooled after it has been taken 
from the molten zinc. While some galvanizers use different grades 
of fuel oil, we have found that better results are obtained by using 
what is known as "mineral lard oil." 

Glycerine 

Glycerine is used in a small plant in very limited quantities. 
Therefore, the small operator can depend on his local druggist for 
what is necessary. In large plants it is usually bought from the 
manufacturers in iron drums holding from ten to twelve hundred 
pounds. 

Aluminum 

This metal is quite commonly used in galvanizing baths to make 
the metal more fluid and improve the appearance of the work. Its 
use has become so common that several concerns now make a busi- 
ness of manufacturing aluminum alloys or fluxing metals for 
galvanizing purposes, selling them under various trade names. The 
different manufacturers of these alloys ha^'e their own methods of 
application ; consequently, we shall not attempt to give any hard 
and fast rules for the use of fluxing metals in a galvanizing bath. 



CHAPTER V 

Pickling 

AS THE first oi^eration in any process of galvanizing or 
tinning is to properly prepare the work to take the coating, 
^ we will give that our first attention by describing the dif- 
ferent methods. Many large concerns use the mechanical pickling 
apparatus shown in Figs. 28 and 29. 

There are several agencies that may be employed in preparing 
work for galvanizing. Sulphuric, muriatic and hydrofluoric acids 
are all valuable agents for this purpose, and the ones most com- 
monly employed. 

The cleaning of work Avith acids preparatory to coating them 
by any process is known as "pickling." Pickling means the re- 
moval of scale and other foreign substances from the surface of 
the metals by the chemical action of the acid. If the material to 
be cleaned is simply soaked in acid the chances are that too much 
of the metal will be dissolved, as the action is not uniform on 
account of the varying density of the acid, and the cleamng is both 
uncertain and uneven. Agitation is therefore desirable. This was 
originally and still is to a great extent accomplished by hand, al- 
though many of the large manufacturers of galvanized sheets, gal- 
vanized"' wire, galvanized pipe, tni plate, cold rolled steel and cold 
roliedv shafting employ mechanical methods tp procure proper 
agitation of the-material in the pickling vats because hand pickling 
of these materials was always insufficient and inefficient. As a 
pickling machine brings mechanical action into play to the extent 
that the material is pickled with about one-half of the acid and 
labor required in hand pickling, we consider it our duty to refer 
to it in this article as well as to illustrate it. The best result is 
•«ebtained by moving the material 1)eing cleaned through the acid 
•with a predetermined velocity. By proper mechanical means the 
sheets (if such are being pickled) are separated and shifted suffi- 
ciently to allow the acid to enter between them and prevent their 
sticking together. The acid washing over the surface has, in con- 
junction with the loosened particles of scale, a scouring action 
which thoroughly cleans the sheets. The uniform action of the 

44 



PICKLING 



45 



acid upon the surface is assisted hy thoroughness of the agitation, 
which does not allow acid layers of different density to form. In 
pickling sheets this feature is of extreme importance. If they are 




Fig. 28 — View of Mechanical Pickling Equipment 



immersed in a vat of improperly agitated acid, layers of varying 
density form so that before the upper parts of the plates are prop- 
erly pickled the lower parts are over-pickled. The above is also 
true with regard to the cleaning of pipe by mechanical means. If 



46 



GALVANIZING AND TINNING 



pipe that is intended for galvanizing is kept in agitation in the 
acid vat by mechanical means, the cost of acid and labor is ma- 
terially reduced and the work much better done. 

While mechanical pickling methods have not been applied to any 
great extent to the cleaning of castings or other small articles, they 
might be applied to marked advantage in many cases, and the ideal 
mechanical method is one that keeps the material being pickled in 
motion instead of one that simply agitates the acid. 




Fig. 29 — A Section Showing Akrangement of Mechanical Picklek 

Acid consumption per ton of material depends upon many cir- 
cumstances. Purity and strength of acid, temperature of the 
pickle, thickness of scale, etc., govern acid consumption. 

The pickling of certain classes of material, mainly sheets for 
tinning or galvanizing, is technically known as "black pickling" 
and "white pickling." Black pickling means the removal of the 
heavy oxide formed during the hot rolling process. White pickling 
means the removal of the film of oxide resulting from the second 
annealing. To have the work properly done, acid must wash over 
all the surfaces all the time; otherwise, as before stated, the ma- 
terial is not pickled uniformly. In pickling sheets for galvanizing 
or tinning the change from one acid vat to another must consume 



PICKLING 47 

ver}^ little time; otherwise, tlie product will accumulate dry acid 
and oxide. 

What we have said thus far regard in<;- pickling applies, of course, 
more particularly to large plants than to the ordinary joljljing 
plant handling miscellaneous work. We will, therefore, treat the 
subject from the standpoint of ordinary requirements, as, in ad- 
dition to acids for preparing work for galvanizing and tinning, 
we have the rolling barrel and the sand blast, both of which can 
be employed to good advantage, especially the sand blast.. Acids, 
however, are an absolute necessity, while the rolling barrel and the 
sand blast are simply valuable auxiliary agents. 

Removing Scale with Sulphuric Acid 

Articles of sheet iron or steel are covered to a greater or less 
extent with scale, which must be removed completely before zinc 
will adhere to them. To accomplish the removal of this scale, and 
also the removal of rust, solutions composed of sulphuric acid and 
water of different degrees of strength are employed. Probably a 
solution composed of one part sulphuric acid to twenty parts of 
water, reckoned by weight, at a temperature of 150 degrees F., 
will answer for as great a variety of requirements as any, although" 
the strength and temperature of the solution may be safely varied 
in the hands of a skilled operator. The trouble to be guarded 
against is over-pickling, by which we mean subjecting the material 
to a solution that is toD strong, or too hot, or for too long a time. 
The effect of over-pickling is apparent, as it results in leaving the 
material full of seams, or when it happens to work that has been 
threaded, in the entire or partial destruction of the threads. 

The length of time required to accomplish the work varies with 
the thickness of the scale. In many cases it is necessary to re- 
move thick spots of scale witli some sharp-pointed tool. The shank 
of an old file sharpened and hardened ansAvers this purpose very 
nicely. Patches of heavy scale are often found rolled into the 
heavier gauges of sheet iron and steel, and they are nearly always 
present on forged work. As that part of the article first becom- 
ing cleaned by the a(ition of the acid would be injured if allowed 
to remain in the acid long enough to remove the heavy scale it is 
necessary to use a tool of some sort to loosen the spots of heavy 
scale. IMaterial having an uneven coating of scale should be cleaned 
in a weaker solution than that having an even coating or that 



48 GALVANIZING AND TINNING 

having a light scale. The reason is that the part of the stock which 
is first cleaned will be over-pickled before the parts having the 
heavier scale are clean. 

Where large quantities of wrouglit iron and steel products are 
pickled or cleaned with sulphuric acid, which must be heated to 
perform its function to best advantage, the fumes arising from the 
pickling solutions are very obnoxious and the conditions in the 
pickling rooms, and sometimes adjacent departments, in some of 
the large plants are almost unbearable, especially in the late fall, 
winter and early spring. 

With the view of overcoming the objectionable features of sul- 
phuric acid, without at the same time sacrificing efficiency or add- 
ing considerably to expense, several substitutes for pickling and 
cleaning wrought iron and steel have been placed on the market 
in recent years. 

"Kleanrite" is referred to by the manufacturers as a "powdered 
compound, soluble in water." Its use requires no change in the 
jjickling equipment. It is used in a solution made up of 1 pound 
of "Kleanrite" to 4 or 5 pounds of water, or may be varied to suit 
any particular or unusual conditions in pickling. For quick re- 
sults the solution is heated to 150 to 200 degrees F. It is claimed 
to pickle without l)urning, and without pitting the metal. It does 
not exhale any disagreeal)le or destructive fumes such as are pres- 
ent when pickling with sulphuric acid. 

"Bdis Compound" is another substitute for pickling acid. It is 
manufactured in the form of dry cakes which are simply dissolved 
in water and brought up to about 200 degrees temperature; in 
other words, it is used just about the same as acid, but being in 
the dry cakes it is very convenient and pleasant to handle, and does 
not start to act on anything until it is dissolved in water. 

When the work has been i^ickled free from scale and rust and 
is perfectly clean, it should be stored for future use in a tank con- 
taining water enough to cover it comjjletely. A in Fig. 3 desig- 
nates tbe tank to be used for pickling the material to remove 
scale, and B in the same illustration denotes the storage tank. 

Eust and scale may be removed by the aid of muriatic acid, 
properly diluted with water, although not as economically as with 
sulphuric acid, but in cases where only small quantities of forg- 
ings or articles made from sheet iron or steel are handled the sul- 
phuric acid solution can be dispensed with entirely and the operator 



PICKLING 49 

can use tlie muriatie acid solution exclusively. A safe "pickle" of 
muriatic acid is one part acid to four parts water, liquid measure. 
If it should be desirable to hasten the cleaning process when using 
the muriatic solution it may be heated to a temperature of 150 
degrees ¥., although the material must be carefully watched to 
prevent over-pickling. 

Cleaning Sandy Castings with Sulphuric Acid 

Castings that are sandy may be cleaned by pouring over them 
a cold solution of sulphuric acid and water, one part acid to six of 
water. Place the castings on an inclined platform and wet them 
frequently with the solution. Continue this operation until the 
sand is loosened, when the castings should be removed and water 
dashed over them to remove all loose sand. This process is gen- 
erally known as "foundry" pickling, and was extensively used at 
one time. Castings that have been subjected to this treatment too 
long will be covered with what appears to be a gummy or greasy 
substance, and will not take the coating of zinc properly unless 
they are left in the metal a long time, and even then they will not 
be nicely coated, but will be rough and covered with thick patches 
of metal. They will not have the smooth finish which properly 
prepared castings have. 

Cleaning Castings with the Aid of Hydrofluoric Acid 

Hydrofluoric acid' has come into almost general use among gal- 
vanizers for the removal of sand. There is very little danger of its 
injuring the iron, and as it dissolves sand readily, it is the ideal 
acid agent. We have subjected an extremely sandy casting to the 
action of a cold, weak solution of hydrofluoric acid for 3 or 4 days 
before the sand was entirely dissolved without any perceptible in- 
jury to the casting itself. Many galvanizers bring the temperature 
of their hydrofluoric pickle to anywhere from 75 to 200 degrees F. 
We believe that it is a serious mistake to make this a common 
practice. There are occasions when it is absolutely necessary that 
the work be accomplished in the quickest possible time; but as a 
general rule plenty of time may be taken for the removal of the 
sand, and it is done much better and more economically and satis- 
factorily ])y the use of a weak, cold solution. In our regular work 
we employ sufficient tank capacity to permit of the castings re- 
maining in a weak, cold solution from 8 to 2-4 hours. Castings 



50 GALVANIZING AND TINNING 

prepared this way for galvanizing will take the zinc readily, cause 
the formation of less dross in the galvanizing kettle, and have 
much better commercial appearance than castings prepared quickly 
in a hot, strong solution. A solution composed of one part acid 
to ten parts water has very little tendency to injure the iron if 
used cold, although we often allow the solution in our tanks to 
fall much below this strength. As a matter of fact, we make up a 
new solution only at long intervals, simply adding a little acid and 
a little water from time to time as necessary. We have found this 
formula very efficient for a quick pickle : 

Hydrofluoric acid (30%), 6 gallons 
Muriatic acid, 4 " 

Water, 40 " 

This solution should be used warm, not hot. The action of the 
muriatic acid hastens the removal of the sand, but is not violent 
enough to injure the casting. 



CHAPTER VI 

Water Rolling, Tumbling and Sand Blasting 

THEKE are many times when the tumbling barrel will be 
found of great value in the cleaning process; especially in 
a plant devoted to miscellaneous work or to the galvanizing 
of malleable or gray iron castings. It not only facilitates the 
process of removing sand from such castings, but can be employed 
to good advantage in removing heavy rust or scale from forgings; 
thus overcoming to a great extent the danger of over-pickling, as 
well as the disagreeable features connected with the use of acids. 
Castings of a character that permit of their being tumbled can 
often be put in proper shape to receive the zinc coating without 
subjecting them to the action of acid, and, in any event, castings 
that have been tumbleil only require a short time in an extremely 
weak solution of hydrofluoric acid. 

Water Rolling 

A piece of wrought iron from which the scale has been removed 
l)y the use of acid will not have the smooth and perfect coating 
that it would have if the scale was removed by rolling. The same 
is true of malleable iron castings. The best and most perfect re- 
sults are obtained by giving the castings a thorough tum1)ling in 
gravel and water, which operation, brings their surface to a state 
of smoothness only equaled by buffing or polishing. Malleable 
castings on which it is desired to obtain a fine finish should in- 
variably be given this treatment. It is also necessary that patterns 
from which castings are made that are designed to be tinned 
should be finished to produce the smoothest surface possible. This 
will help to shorten the tumbling operation. 

Some tinners not only roll their castings in gravel and water, 
but for the purpose of obtaining a smoother surface than can be 
obtained by this method they roll them with scraps of leather, the 
entire operation often requiring 30 or 40 hours. Water rolling is 
so common and so thoroughly understood that we consider it un- 
necessary to give detailed instructions regarding the apparatus to 
be used or the methods employed. There are several concerns who 

51 



52 GALVANIZING AND TINNING 

make the manufacture of rolling barrels for this purpose a spe- 
cialty, and the cheapest method to adopt when equipping a tinning 
plant with wet rolling barrels is to buy the outfit complete from a 
manufacturer who has made a study of the business. 

Dry Tumbling 

Iron castings as they come from the foundry always have more 
or less sand upon them and castings of large size or peculiar shape 
often have patches or pockets of sand burnt into their surface, 
which cannot readily be removed by pickling. One cheap and 
efficient way of removing this sand is by dry "tumbling/' and this 
method has been used for years by iron foundries to clean their 
castings, and, at the same time, to improve their appearance by 
brightening and smoothing their surfaces, therefor dry tumbling 
serves two important purposes, cleaning and polishing, and all 
who are familiar with foundry practice are more or less familiar 
with tumbling. There are several types of dry tumbling barrels 
on the market made by different manufacturers, but most of them 
are cylindrical in form and the most improved outfits are designed 
to be fitted with a system of pipes and fan for removing dust from 
the barrels. This dust would otherwise go off in the room and 
is sometimes quite objectionable. 

Most castings are of such shape that they could not be thor- 
oughly cleaned or polished in the tumbling barrel, unless some 
smaller objects were tumbled with them, which would work into 
the holes or identations on their surface. For this purpose iron 
stars, commonly called jack stones, diamonds or cubes are used, 
all of which in foundry parlance are called "shot." Very small 
castings with fairly smooth surfaces can oftentimes be tumbled 
clean without the use of shot. 

To load a tumbling barrel put in first a thin layer of shot and 
then a layer of castings and continue in this manner, one layer 
upon another, until the barrel is nearly filled. Some space must be 
left for the castings and shot to move about in as the barrels re- 
volve. The friction caused by this moving or "tumbling" cleans 
the castings. If fragile gray iron castings are being tumbled, too 
much space must not be left in the barrel, as such castings would 
be broken by the shock of tumbling with too much force. One- 
third shot and two-thirds castings (by bulk) is about the right 
proportion for ordinary tumbling, but the proportion should be 



WATER ROLLING, TUMBLING AND SAND BLASTING 53 



changed to suit the individual requirements of each lot of castings 
using more shot for hollow castings, or castings with a very uneven 
surface and less for plain castings with comparatively smooth sur- 
faces. After the harrel is loaded and started very hard pounding 
of its contents will warn the operator that the harrel is not prop- 
erly packed and castings may he injured if allowed to (^ntinue 
tumhling under these conditions. 

In tumhling for galvanizing let the castings remain in flie barrel 
until all sand possible is removed without injuring them, as this 
is the most important object of tumbling for galvanizing. Practice 
makes perfect and with intelligent study of the problem an opera- 
tor can, after a time, tumble castings so clean that they will require 
very little, if any, pickling before galvanizing. The cleaning of 
many kinds of work for galvanizing is greatly simplified by the use 
of the tumbling barrel. Old rusty chains and castings or wrought 
iron forgings which are badly rusted can usually be cleaned to good 
advantage in this way. Old paint can also be removed from arti- 
cles which can be tumbled much easier and better in many cases 
by tumbling than by any other means. In addition to cleaning 
cheaply, tumbling also makes the surface of castings smooth, which 
greatly improves the appearance of the galvanizing. 

The Wet Tumbling Barrel 

The barrel is constructed in accordance with the plan shown in 
Figs. 30A, 3013 and 30C. The points where in this barrel differs 
from the ordinary wet rolling barrel are: that it is built very 
heavy and strong, is provided with valves for the escape of gases 
generated by the chemi- 
cals used, and the open- 
ing where the barrel is 
filled is arranged to close 
tightly. 

For general work we 

prefer a barrel 48 inches 

long and 24 inches in 

diameter. The shell we 

make of f-inch boiler' 

^ , . Fig. 30a — Tumbling Babeel 

iron, and use cast iron 

heads 1^ inches thick. The manhole cover we make 1 inch thick, 

and have it well ribbed to give additional strength. 




54 



GALVANIZING AND TINNING 



Fig. SOB is a plan view of the ])arrel, and it also shows the 
receiving tank IT, designated in the ground plan, Fig. 51, as B, 

Fig. 30A is an elevation of Fig. SOB. 

Fig. SOC gives the details of the harrel, in which A is an end 
view of the trunnions B and C, and D is a view of the pillow 
blocks supporting the harrel, and E is the pillow block for the 
pinion shaft; F is a valve for the escape of gas, and Gr is a view 
of the end of the barrel on which the valves F are placed^, while 
H shows the rolling barrel cover. 

Preparing the Castings for the Tumbling Barrel 

The details of cleaning having been carefully attended to, place 
the castings in the tumbling barrel, together with a quantity of 
ordinary iron "stars," such as used in dry tumbling, being care- 
ful to load the l)arrel in such a Avay as to prevent breaking or 
wearing the corners of the castings. Tea kettles should be filled 
full of stars or shot l^efore placing them iii the tumbling barrel, 
and light, delicate castings should l)e packed tightly enough to 
prevent l:»reaking. Stars or shot sufficient to fill the barrel 
about one-fourth full will be found the most desirable quan- 
tity for ordinary work, 
d(l lLl.-L' -I.JH;ddidl lI^ although on hollow ware 

much more are needed, 
or enough to fill up 
nearly all the vacant 
space. After the barrel 
has 1)een loaded in the 
way described, put in 
water sufficient to fill it 
about three-fourths full, 
then add 15 pounds of 
commercial muriatic acid 
and 2 pounds of gray 
granulated sal ammo- 
niac. The barrel is now 
ready to be closed and 
started, presuming that the operator has examined the valves to 
see that they are in j^erfect working order previous to loading the 
barrel. 

After the barrel has been in motion from 5 to 15 minutes, de- 




FiG. 30b — Top View of Tumbling Barrel 



WATER ROLLING, TUMBLING AND SAND BLASTING 55 

pending on the temperature of the water used, there will l)c formed 
sufficient gas to cause the valves to open. The escape of gas will 
be accompanied by quantities of the solution, and the end of 
the barrel on which the valves are placed should be inclosed, un- 
less the barrel is set up in a room itself. 

The time which castings should be rolled in this solution varies 
from 2^ to 5 hours. Soft, smooth castings will take a nice coat- 
ing after a rolling of 2^ hours, while to obtain the same results 
on hard iron, iron cleaned by the use of sulphuric acid, hollow 
ware and tea kettles and castings having a black lead facing, 5 
or more hours in the barrel may be necessary. It is safe to say 
that 3^ hours is sufficient to properly roll ordinary castings if the 
barrel turns 40 revolutions a minute. For hollow ware, tea ket- 
tles and very delicate castings the barrel should not attain a 
speed of over 30 revolutions per minute. After the castings have 
been rolled in the solution the required time, open the barrel 
and cover its contents with water immediately. Do not let time 
be wasted in getting the castings covered with water, as a slight 
exposure to the air will cause them to oxidize and prevent them 
from taking the tin. If the castings are properly prepared — that 
is, if they have been rolled in the solution long enough — they will 
be in such condition after rinsing that they will not soil a white 
cloth, rubbed on their surface, to any extent. 

Should it- be found that the castings are not properly prepared 
(which is done by putting one or two of the pieces through the 
regular treatment), the barrel should be re-charged by adding 6 
pounds of muriatic acid and allowed to run about an hour longer. 
In rolling castings plans should he made to complete the work 
before the stopping of the power at noon and night. 3^ hours 
being required on an average to prepare iron in the rolling bar- 
rel, it is easy to arrange to start the barrel in time to complete 
one batch in the morning and one in the afternoon. This would 
furnish work enough to keep two hands engaged, although one 
set of kettles would take care of all the iron that could be pre- 
pared in a barrel of the size we show; viz., 2 feet in diameter 
by 4 feet in length. 

If the castings are quite soft and clean three batches may be 
prepared in ten hours, in which case the second batch should be 
in the barrel in time to give it at least one hour's rolling before 
the power is stoj^ped at noon. When a batch of iron is left in 



56 



GALVANIZING AND TINNING 



the barrel during the noon hour, leave the barrel closed, and in a 
position Avhere one of the valves will be up, with its opening above 
the solution in the barrel. Unless this is done the valves may 
open and allow the solution to escape, necessitating the re-charging 
of the barrel. If a batch of castings is not completed in season, 
to remove it to the storage tank before the time for stopping the 





^ 







>^l(^> 



WfW° 



r 



l©8 



Fig. 30c — Details of Tumbling Barrel Equipment 

power at night, remove the cover, and allow enough fresh water 
to flow into the barrel to displace at least half of the solution, 
and leave it in that condition until morning, taking care that the 
valves do not leak, that the iron is completely covered, and that 
the water is not left running, as iron will rust in running water 
even if the water covers it. 

In rolling a batch of castings it will often be found that a 
black foam will rise to the surface of the solution when the bar- 
rel is opened. This is formed by the iron dust left on castings 
that are cleaned by dry tumbling, and it will also be found when 



WATER ROLLING, TUMBLING AND SAND BLASTING 57 

preparing castings that have l)eon faced with foiUKlry facing of 
any sort. When this foam or scum is present, let water flow into 
the ])arrol, with the opening in a position that will allow the 
ohjectionable matter to float off. The first one or two batches 
prepared in a new barrel are liable to give trouble in tinning unless 
the inside of the barrel, with the shot to be used, is cleaned with 
a strong alkali solution. The simplest way is to put the shot into 
the barrel, and, after filling it about half full of strong, hot alkali 
solution, close the barrel and allow it to run an hour or more, 
after which the interior of the barrel and the shot used should 
be rinsed with plenty of clean water. 

It sometimes happens that castings are encountered which have 
a ground work of delicate design into which the sand has been 
burned. If such castings are placed in the rolling barrel with 
a good quantity of shot and given two or three hours' rolling in 
a solution of hydrofluoric acid and water, 1 part acid to ?5 or 100 
of water, they will be cleaned very nicely. AYlien this is done let 
the hydrofluoric solution run out of the barrel before charging it 
with the regular solution of muriatic acid, sal ammoniac and 
water. 

The operator must bear in mind at all times that as a safe- 
guard against accident he must see that the valves on the rolling 
barrel are kept in good working order. These valves should be 
adjusted to open at a pressure of 40 pounds. If, by reason of a 
leak in any part of the barrel, gas is not generated the work 
will not tin properly. Do not approach the barrel with a light 
at any time when the gas is escaping, or at any time when the 
gas is being generated in the barrel. If after stopping the barrel 
it is found that the valves leak, as they may from becoming clogged, 
stop the leak, as the solution will escape, thereby allowing the 
work to oxidize. Badly oxidized eastings will not tin. The solu- 
tion contained in tank P, Fig. 51, is calculated to remove a light 
oxide, but castings that are heavily oxidized must be re-rolled. 

Storirxg the Castings After Tumbling 

As soon as the operator has determined that the castings are 
properly rolled for tinning he proceeds to dump the contents of 
the tumbling barrel into the receiving tank, located directly under 
the barrel. The cubic contents of this tank should be about one- 
third greater than the rolling barrel. From this receiving tank 



58 GALVANIZING AND TINNING 

the castings should be removed to the storage tank designated 
C in Fig. 51. A good-sized coke fork is best for handling the 
castings from tank to tank, as it lets the shot or stars fall to the 
floor sejDarate from the castings. 

In placing the castings in the storage tank care should be 
taken to have those with depressions or cavities go under the water 
with the openings up. In other words, castings of a shape that 
would retain pockets of air under the water should be so placed 
that no air can be retained. If air is retained there will be a 
rusty place formed on the casting to which the tin will not adhere. 
The water in storage tank C, Fig. 51, will in a short time become 
charged with the acid solution from the rolling barrel unless it 
is changed frequently. If much acid is present in the water it 
will impair the action of the alkali solution into which the cast- 
ings i3ass directly from this tank. If a few jDounds of the alkali 
selected for use (caustic soda or soda ash) is added two or three 
times a week to the alkali solution, it will do its work properly 
for some time, although it is best to clean out the tank and make 
up fresh solution once in two weeks when it is in constant use. 

Cleaning Work with the Sand Blast 

While the art of sand blasting is old, its use in preparing mate- 
rial to be galvanized or tinned is comparatively new. 

Not so many years ago the process of tinning common gray 
iron was considered a great secret. As a matter of fact, there were 
only one or two concerns able to do it on a commercial ))asis, and 
their operation was confined to comparatively small castings. The 
methods employed were complicated and expensive. The use of 
the sand blast has made the tinning of gray iron a simple matter, 
especially in the case of unusually large or fragile castings. 

While the best commercial appearance is still obtained by use 
of the wet rolling Ijarrel, there are many kinds of castings that it 
is impracticable to prepare in that manner owing to their size or 
delicate construction. To obtain even fairly economical time re- 
sults with tlie water rolling barrel it is necessary to have it re- 
volve not less than 35 or 40 revolutions per minute, and even with 
this speed it takes no less than 3 hours to jDroperly prepare a batch 
of castings for tinning, and often a much longer time. On the 
other hand, the sand blast barrel will prepare a similar batch of 
castings in from 15 to 20 minutes. 



WATER ROLLING, TUMBLING AND SAND BLASTING 59 

Cold galvanizinfl^ as well as Sherardizing can he done on work 
coming direct from the sand hlast, practically eliminating the use 
of acids, and a much brighter coating is obtained. As acid works 
more or less into castings in the cleaning process, even its partial 
elimination is another distinct feature in favor of sand l)lasting 
for any process of coating. 

Another feature in favor of the sand blast is that old work can be 
thoroughly and quickly cleaned by this method. It is our prac- 
tice to use a pressure type of hose machine in the cleaning, for hot 
galvanizing of -old anchors, old anchor chain, and in fact old 
material of a heavy nature of almost every kind. 



TRADE MARK 




ATENT APPHe 



Fig. 31 — A Simple Two-hose Type of Sand Blast 

The large variety of shapes and weights of castings makes it 
impossible for us to give a definite time for cleaning by this 
method. In a general way we will say that such articles as food 
choppers, saddlery hardware, etc., when cleaned in a sand blast 
barrel will require from 10 to 15 minutes, the consumption of 
free air per minute being 135 cubic feet at 60 pounds pressure, 
while heavier castings or old work that is badly rusted may re- 
quire a considerably longer time. For steel castings and forgings 
a higher pressure will give the best results. This applies to both 
the hose and the automatic machine type. 

The value of the sand Ijlast for plating plants in general is only 
beginning to be appreciated, and while it does not entirely elimi- 
nate the use of acids, it goes a long ways in that direction and is 
one means of making working conditions in a hot galvanizing 
plant, which are bad enough at best, much more endurable. 

That the subject of sand blasting and the apparatus referred 



60 



GALVANIZING AND TINNING 



to may be better understood, we refer to the same herewith more 
full,y. The term sand blast in its simplest form means a stream 
of sand and air under pressure. In this condition the sand gather- 
ing velocity as it is carried along with the air strikes the object in 
its path with great force. The cutting action of the blast is greater 
when the blow is slantwise rather than straight against the object. 

A simple form of sand blast de- 
vice can be made from a Y pipe fit- 
ting, using regular stock fittings to 
complete the job, but the action of 
the lilast would destroy the several 
parts after a few hours' service. Far 
better satisfaction will l^e obtained by 
purchasing an outfit like that shown 
in Fig. 31. One popular and service- 
able suction sand blast outfit consist- 
ing of cast iron nozzle with remov- 
able air tip, easily replaceable hard 
iron blast tip, air valve, sand hose, 
sand blast helmet and gloves, costing 
not over $25.00. In this type of ap- 
paratus the end of the sand hose is 
placed in a pail or pile of sand and 
the air turned on at the nozzle. 

The next, and most widely-known 
system, is the pressure or single hose 
type, Avhere the sand is placed in a 
closed tank and air admitted to the 
same under the same initial pressure 
as that to be used in the blast. In 
this machine, see illustration, Fig. 33, 
there is a mixing chamber at the bottom into which the sand is fed 
through a valve, and the sand mixing with the air which is ad- 
mitted through a separate opening is discharged through a single 
hose. At the outer end of the hose is a hard iron nozzle holder, 
having means for replacing the hard iron tip which wears away 
very rapidly. The hose must be specially made for sand blast use, 
the core being composed of practically pure rubber. 

The present tendency in sand blast practice is toward higher 
air pressures, say 60 pounds, using smaller nozzles and hose. It is 
easier for the operator to handle this apparatus than the more cum- 




FiG. 32 — Single Hose Type 
Sand Blast Apparatus 



WATER ROLLING, nTMBLING AND SAND BLASTING 61 

bersome where lower pressures are used. The maintenance cost is 
also less. A very satisfactory outfit consists of tank, one-inch 
hose and :^-inch blast nozzle, the consumption of free air at 60 
pounds pressure being about 67 cubic feet and the power required 
to compress the air approximately 10 H. P. 

The present tendency is to get away from the hand operated 
blast owing to the reluctance of men to follow this work continu- 
ously. Accordingly self-contained, dustless machines have l)een 
designed which handle tons of material in a day. These are made 
in the form of a rotary table, a sliding table or planer type and 
revolving barrel. 

Sand Blast Rolling Barrel 

For cleaning small and medium-sized castings, forgings, etc., 
the sand blast rolling process is to be preferred in many ways. A 
popular type is shown in Fig. 33. 

The self-contained feature confining the blasting operation and 
recovery of abrasive to the inside of harrel makes it a dustless, 
as well as a more efficient, method. 

The process is entirely automatic after the work is placed in 
machine, and the operator is at liberty to attend to other matters 
if he so desires. 

Unlike the tumbling mill running approximately 40 R.P.M., 
the sand blast rolling barrel revolves 2 R.P.M., making it possible 
to clean fragile castings without rounding the corners, etc. 

This method has proven valuable in cleaning letters or orna- 
mental design work on castings, the slow movement of barrel pre- 
vents defacement and the blast removes all dirt and cleans them 
perfectly. 

The inner barrel B in Figs. 34a and 34b is made from heavy 
sheet steel, one-half inch thick, having a number of holes in same 
which allows the sand, after coming from the blast nozzle F and 
striking castings, to fall through at bottom of inner l:)arrel B to 
outer shell A. As the barrel revolves (direction of arroAv) the sand 
or grit falls into buckets C and is carried to the top of the l)arrel, 
where, by its own gravitation, it falls back through the holes which 
it entered, passing through screen E, removing all foreign sub- 
stances, into sand-hopper D, ready to be used again. 

G is the exhaust pipe for removing dust, H the slide valve in 
hopper, I the cast steel hopper support, J the petcock for drip, 
K the compressed air inlet, L the exhaust outlet. 



62 



GALVANIZING AND TINNING 



While it is possible to do sand blasting in an open space, yet 
the dust arising from the operation is so objectionable that it is 
customary to provide a room for this work, the same to be con- 
nected to an exhaust fan having capacity siifficient to change the 
air in the room not less than five times every minute. Fresh air 




Fig. 33 — Self-contained Sand Blast Barrel 



must be admitted at a point as far distant from the exhaust con- 
nection as possible. The smaller the room the better, for less 
power will be required to run the fan. The walls of the room 
are usually of wood, nailed on and easily rencAved as occasion de- 
mands. A most satisfactory lining is discarded fire service hose, 
which should be sjDlit and, with the inner side facing out, nailed to 
the siding. The operator must be provided with a helmet and 
should also use a respirator. Leather gloves are also a necessity. 



WATER ROLLING, TUMBLING AND SAND BLASTING 63 




Fig. 34a — Front View, Showing Details of Sand Blast Barrel 



6 



i 



«t 






.A 



~-4?f 



U-'-: 







©I 4:>®::~v 




■S-F 



J_©i] 



^yt:^^--^-^--iS= 



_^_ ^_B._____^ 




Fig. 34b — Side View, Showing Details of Sand Blast Barrel 



64 GALVANIZING AND TINNING 

It is always important to use a good hard, washed quality of 
silica sand, passing the same through an 8 or 10 mesh screen for 
general work. The sand must always he dry, likewise it is im- 
portant that the air should he dry. In the case of a pressure or 
closed tank system, the very strictest attention must he paid to 
these particulars. 

Diamond Grit and Steel Shot Used as Substitute for Sand 

In many instances sand is being replaced by steel grit or chilled 
shot. Both have their particular field, the shot No. 5 Globe, or 
16/30 Harrison, giving most excellent service in connection with 
the sand blast barrel. As this class of material is expensive, it 
must not be allowed to go to waste, good floors and tight rooms 
being required when used with the hose machine. 

Diamond grit and steel shot have proven a very satisfactory sub- 
stitute for sand, though opinions difi^er as to their relative value 
due to local conditions. 

Diamond grit is angular in shaj^e and otherwise known as 
crushed steel ; its edges are sharp and it has all the cutting qual- 
ities of sand. 

There are several advantages in using this material Avhich are 
due to its slow deterioration. It does not break up like sand and, 
therefore, may be used many times before replacement is neces- 
sary. It is dustless in itself and naturally eliminates the dust that 
would otherwise be generated by the use of sand. 

This material is made in a number of sizes, enabling the user 
to adapt a size satisfactory to the finish desired. 

Steel shot carries the same general advantages as grit, though, 
])eing glol3ular in form, its actual cutting qualities are not so 
severe. Its action is more of a peaning effect ratlier than cutting, 
and castings cleaned have a tendency toward a shiny appearance 
rather than the sand blast finish as produced by sand or grit. 

Preparing the Cleaned Work for Dipping 

To enable the zinc to unite with the work properly, a solution 
of muriatic acid and water is used. This not only serves as a 
flux, but removes any rust that has formed on the work in the 
operation of inspection. It will naturally be inferred from the 
above that all work should be carefully inspected to determine 
whether the cleaning process has been properly performed before 
it is subjected to the muriatic acid treatment. While the char- 



WATER ROLLING, TUMBLING AND SAND BLASTING 65 

actor of this muriatic acid dip may be varied, we use ordinarily a 
solution composed of one-half acid and one-half water, liquid 
measure. 

Some galvanizers add 1 pound of sal ammoniac to a gallon of 
the mixture, but, in inour opinion, the advantage gained does not 
warrant the expense. Tank C, Fig. 3, is for containing this 
mixture. 

Drying the Work 

From tank C, Fig. 3, or, in other words, from the muriatic acid, 
the work is taken to the place provided for drying it. The 
position of this drying arrangement is designated E in Fig. 3. A 
drying arrangement for a limited amount of work may be the 
plates covering the fires that heat the kettle. If the work to be 
handled only amounts to a few hundred pounds per day, it can be 
dried in this way. If, however, the amount of work necessitates 
keeping the kettle in constant operation, a drying arrangement 
such as shown in Figs. 18 to 23 should be provided. Sheets and 
pipe should be dried in an oven. 

The location of this drying arrangement is a mere matter of 
choice. In Fig. 3 we show it located at one end of the kettle. 
The castings or other work to be dried prior to galvanizing are 
placed, while still wet with muriatic acid, on the heavy cast iron 
top plates of this dryer directly over the fire box, where they are 
allowed to remain until thoroughly dry, when they should be passed 
to the end of the dryer farthest from the fire to stay until needed. 
If allowed to remain on the hottest part of the plate for too long 
a time, the work will become too hot and the acid burned off, which 
will necessitate re-dipping them in the muriatic acid before they 
can be galvanized satisfactorily. When properly dried, the salts 
formed by the muriatic acid should show on the surface of the 
work in the form, of a white powder. Work that has been prepared 
for dipping and dried should not be allowed to get cold; and if 
more material has been prepared for dipping than can be finished, 
it should not be allowed to remain on the dried over night, but 
returned to the water tank. It should be remembered that rusting 
is merely oxidation; and freshly cleaned surfaces readily attract 
free oxygen from the air. While moisture assists rapid oxidation, 
a total immersion in water is an admirable preventative of rust- 
ing. It should, of course, be re-dipped in the muriatic solution and 
dried again before putting it into the galvanizing kettle. 



CHAPTER Vn 

Hot Process of Galvanizing 

Filling a New Kettle 

WHEN the galvanizing kettle has been properly bricked 
in ready for use considerable care must be exercised in 
filling it with spelter to prevent the kettle from being 
ruined when the fires are started. In the first place, a suffi- 
cient quantity of lead should be put in the kettle to insure a 
depth of not less than 6 inches when molten. If the kettle is more 
than 30 inches deep, lead should be introduced to insure a 
depth of at least 8 inches. When dross forms in the process of 
galvanizing this lead serves as a "cushion'^ for it to rest upon. 
Lead and spelter do not mix under these conditions, the lead being 
of a greater specific gravity, remains at the bottom of the kettle, 
and no amount of stirring can cause any considerable quantity to 
be permanently mixed with the spelter. As a matter of fact, if 
lead is present in the spelter itself, as it sometimes is, most of it 
settles to the bottom of the kettle when the sj)elter becomes melted. 
The lead not only serves as a cushion for the zinc dross to rest 
upon as it forms, but greatly facilitates the removal of the dross 
when necessary. It is also a protection for the bottom of the kettle 
and keeps the spelter and dross even or slightly above the fire line, 
as it should be. 

In filling the kettle with the slabs of spelter, place them on edge 
in such a way that their flat surface will lie as closely as possible 
to the sides of the kettle. By exercising a little ingenuity the 
slabs can be placed so as to practically cover the sides of the kettle. 
This method of packing the slabs will materially lessen the danger 
of burning the kettle at the first firing, as there is cold zinc against 
all the heated surface. These slabs should also be so arranged that, 
as the outside ones melt, those next to them will be forced outward 
against the sides of the kettle. To the inexperienced this may 
seem an unimportant matter, but we can assure the reader that 
many kettles have been ruined at the first firing through failure 
to give proper attention to these details. 

66 



HOT PROCESS OF GALVANIZING G7 

When a galvanizing ])lant has an equipment of more than one 
kettle it is a good plan to bail molten metal from a kettle already 
in use into the one that is being put into operation for the first 
time, after the slabs have been properly arranged, and before 
starting the fires. EefiU the kettle in operation with new metal, 
replacing what has thus been taken out. 

Firing a New Kettle 

In heating up a kettle for the first time great care should be 
exercised that the work is not hurried. Under no circumstances 
attempt to melt out a kettle for the first time in less than 36 
hours. Until the spelter commences to melt the fuel should not 
be allowed to attain a depth of more than 12 or 15 inches in the 
fire boxes, and the slides that close the draft holes should be so 
regulated that the fires will not burn too strongly. We repeat 
that plenty of time should be taken to melt the metal in a new 
kettle the first time; otherwise, one may be put to heavy expense 
for replacing a burned out kettle, to say nothing of the loss result- 
ing from over-heating the zinc. As the metal melts the depth of 
fuel may be increased, but it should never be more than 3 or 4 
inches above the molten metal in the kettle. Of course, it is rather 
difficult to determine just the depth of the molten metal, but it 
is easy to be on the safe side even if a longer time is taken for the 
"melting out" operation than is actually necessary. 

The Temperature of the Zinc 

The question of the temperature of the zinc is the most difficult 
to learn; for the reason that different kinds of work demand that 
different temperatures be maintained. A kettle of zinc at the 
proper heat for wire or wire cloth would be much too hot for 
galvanizing castings of either gray or malleable iron, while with 
the metal at the proper heat or heavy work, it would be impossible 
to coat small work properly, even if the material was the same. 
Large pieces demand that the galvanizing bath be maintained at 
a low temperature. Small work that is strung on wires for dipping 
in the galvanizing bath demands a higher heat than heavy pieces. 
Work that is galvanized in baskets often requires a still higher 
heat than work that is strung on wires, as hereafter described. 

We shall give the degrees of heat that a pyrometer should indi- 
cate when different kinds of work are being done, basing the rules 



68 GALVANIZING AND TINNING 

given on the supposition that Avhen the metal is barely melted — 
that is, at a temperature that would just keep it in a liquid state, 
the pyrometer indicates 750 degrees of heat. We shall also give 
the best rules possible for determining the proper temperature by 
the appearance of the metal and by other signs. 

Large gray iron castings require that the metal be at the lowest 
temperature possible and still have it liquid. At about this tem- 
perature it will be silver white in color, will burn sal ammoniac 
slowly when thrown on its surface, and when a skimmer is passed 
over its surface the oxide will be slow in appearing. With the 
metal in this condition the pyrometer should indicate about 800 
degrees of heat. This temperature is also suitable for galvanizing 
very thin castings that are intended to be "spangled" or to have a 
crystallized appearance — for example, sinks and like work. 

For work that is drawn through the clear metal the pyrometer 
should indicate not less than 850 degrees. At this temperature 
the metal should have a slightly bluish cast, burn sal ammoniac 
moderately quick and show the oxide in a few seconds after the 
skimmer has been passed over its surface. This temperature is 
about right for galvanizing wrought iron pipe, the cheaper grades 
of sheet iron and goods made from it, such as coal hods, ash cans 
and chamber pails. Heavy malleable iron castings will also coat 
nicely at this heat. 

For small work, such as nails, and in fact, almost any work that 
is done in baskets or strung on wires and drawn through flux, the 
pyrometer should indicate not less than 900 and not more than 
925 degrees F. The metal at this heat should burn sal ammoniac 
quickly and oxidize quickly, and will be quite blue in color. This 
temperature is about right for sheet steel and articles made from 
it, as well as steel pipe. 

We wish to impress upon the reader that these rules for tem- 
perature are based on the supposition that the galvanizing bath is 
composed of strictly Prime Western Spelter that has not been 
subjected to overheating, and that the bath is practically fresh by 
reason of recent starting or recent drossing and re-filling with 
new metal. If "Eemelt" spelter is used exclusively, or even par- 
tially, the proper degrees of heat can onl}^ be determined by ob- 
servation and experience. Therefore, we repeat that no hard and 
fast rules for operating the bath exclusively by the pyrometer can 
be given. 



HOT PROCESS OF GALVANIZING 60 

Dipping the Work in the Molten Zinc 

We will describe the manner oL' handling several different ar- 
ticles as a general guide for dipping all kinds of work. Consider- 
able skill is required to bring work out of the molten metal and 
cool it in such a manner that the surface will be smooth, free from 
blisters and without lumps of surplus metal attached. 

Before commencing to dip the work, cover part of the surface 
of the molten zinc witli a sal ammoniac flux to keep the oxidized 
metal from adhering to the material. To prepare this flux, sprinkle 
a few'handfuls of sal ammoniac on the surface of the bath, and as 
soon as it is melted add a few drops of glycerine. This will cause 
the flux to thicken somewhat and will prevent it, in a measure, 
from covering the entire surface of the metal. The glycerine also 
causes the flux to remain stationary, so that when the operator is 
ready to draw work from the bath the flux will not cover the space 
he has cleared with his skimmer for so doing. The tool desig- 
nated E in Fig. 25 is a skimmer used for clearing the surface of 
the metal before drawing work from the bath. 

The flux not only prevents the zinc from oxidizing, but also as- 
sists the metal in adhering quickly and evenly to the work. Keep 
the flux fresh by adding more sal ammoniac from time to time as 
required. 

We will suppose an article to be dipped is a cast iron sink or 
some similar thin casting, in which case have the metal at the 
temperature first described under the heading "The Temperature 
of the Zinc." After satisfying himself that the casting has been 
heated until it is perfectly dry, the operator catches the article 
with a pair of tongs and plunges or drops it as quickly as possible, 
without causing the metal to spatter, through the flux into the 
molten zinc. He must keep the article beneath the surface until 
it becomes as hot as the zinc itself. After the article has been in 
the bath a few minutes it should be rinsed or washed around in 
the metal in such a way that the flux will come in contact with all 
parts of it. AVhen the article is thoroughly coated clear a space on 
the surface of the molten zinc with the skimmer, sprinkle on a little 
dry white sal ammoniac, and draw the article slowly from the 
metal. 

In performing this operation catch the article with the tongs 
in such a way that the part they grasp will be the last to leave 



70 GALVANIZING AND TINNING 

the zinc. Do not lift tlie article clear of the metal with the 
tongs you use in the hath, lait provide a second pair to complete 
its removal and to handle it until cooled. Hold the article in such 
a position as to cause the surplus metal to flow to one point, and 
just as the drop starts to harden remove it with a stiff hrush or 
an old file. Expose the article to the air until crystals appear, 
and then Ijrush it lightly with a brush wet in clear water. Do not 
dip the article in water, especially if it is a very thin casting, as 
that would be quite likely to l)reak it, and the coating would not 
be as bright as if left to cool gradually after l)rushing with the 
wet brush. Thick, heavy castings may be dipped in water at once 
on removing them from the molten metal. 

Coal hods and similar goods of sheet steel or iron only need be 
left, in the bath a few seconds. The flux through wliich they pass 
should be confined at one end of the kettle ])y a piece of sheet iron 
long enough to go across the kettle from side to side. This is called 
a "flux guard," and it should enter tlie metal about 2 inches, with 
the upper edge as high or a little higher than the sides of the 
kettle. In galvanizing sheet metal ware the flux should be made to 
foam up nearly to the top of the kettle l)y using glycerine. The 
goods should be passed through the flux under the guard to the 
end of the kettle that is kept clean. In passing the article under 
the flux guard, keep the opening up so that none of the flux will 
be carried along with it. Eemove the article from the metal in the 
way described for sinks and similar articles, but do not sprinkle the 
clear surface of the zinc with sal ammoniac. Allow the work to 
cool in the air. If any particles of flux have adhered to the work 
while drawing it from tlie molten metal, remove them with a wet 
brush while the article is still hot. 

Some articles can be galvanized to best advantage by stringing 
them on stout wires about 2 feet long. When this method is em- 
ployed, string on a number of the pieces and then bring both ends 
of the wire together and clinch them securely. For suspending 
work in the metal whicli is strung this way, use a hook, shaped in 
the form sliown by Fig. 25 and designated G. Provide several of 
these hooks, so that a batch may always be ready for removal from 
the kettle when the previous one has been removed. A piece of 
f-incli round iron, bent in the shape of the letter S, may be used 
to remove the strings of castings from the hooks, and also foi 
handling them until they are cooled. The wires C and D, Fig. 25, 



HOT PROCESS OP CALVANIZINO 71 

are also intended for stringijig small articles for the purpose of 
dij)ping them in the molten metal. 

In handling small articles on any of these wires after they are 
drawn from the metal, use a shaking motion that will free them of 
surplus metal, and also prevent their sticking to each other when 
plunged in the water. Some practice will be necessary before this 
can be done properly. 

It is a good plan to warm the cooling water slightly for cooling 
some articles, and to have a thin film of oil on the surface. Small 
articles strung on wires may be drawn from the clear metal after 
sprinkling on a small quantity of powdered sal ammoniac, or may 
be drawn through a clean, thin flux of sal ammoniac, to which a 
few extra drops of glycerine have been added. If the latter method 
is used, as it should be if the articles are such as are liable to rub 
and stick together, oil should not be used on the cooling water. 

Small work that cannot be strung on wires may be galvanized in 
a wire or sheet iron basket. We have already described these, and 
they are designated in Fig. 25 as A and B. 

When baskets are employed, the flux should be of such con- 
sistency that it will flow freely among the work. A block of iron 
should be placed on the brickwork beside the kettle in such a 
position that the operator can rest the handle of his basket across 
the block with the basket hanging over the kettle. Using this block 
as a rest, the operator should shake the basket up and down sharply 
for several seconds after if has been drawn from the bath to free 
the work of surplus metal, and when this is accomplished he should 
dump them into the water to cool, after which, dry them off by dip- 
ping in boiling water and throwing them into dry sawdust. Nails 
or tacks may be shaken out of the basket onto an iron plate, placed 
at an angle, over a tub of water to separate them. The plate 
should be inclined sufficiently for the work to slide into the water 
readily. 

Considerable difficulty is experienced in removing the surplus 
zinc from small articles, such as nails, tacks, bolts, nuts, washers, 
rivets, screw eyes, screws and sheet metal or wire specialties when 
hot galvanizing them imless mechanical means for accomplishing 
this purpose can be employed. This fact has been responsible for 
the invention of several different machines and devices intended 
to remove the surplus metal after the articles have been taken 
from the molten zinc. Notable among these is the "Porter Ma- 



72 GALVANIZING AND TINNING 

chine/' which, according to the inventor, will handle anything 
from a small tack to a 60-penny nail at the rate of from 2000 to 
3000 pounds per hour. This machine removes all unnecessary 
surplus metal by means of beaters or fans, cools the articles with- 
out their coming into contact with water, and automatically de- 
livers them into kegs or boxes ready for shipment. As this ma- 
chine occupies considerable space and has a large capacity it is 
best adapted to the large producer and has been used by such con- 
cerns for some time past. Another means of accomplishing the 
same result is found in the "Watrous Machine," which utilizes the 
action of centrifugal force for throwing off the surplus metal while 
it is still molten. This machine is claimed by the inventor to 
have been in successful operation for some time by several manu- 
facturers. 

Various other machines designed for the same purpose are 
claimed by their enthusiastic inventors to attain remarkable re- 
sults, but the prospective purchaser of any such device or machine 
should thoroughly investigate the matter before making a decision, 
as any of them may have limitations or objectionable features which 
can best be learned from some one other than the inventor who has 
had actual experience with the device. Eemoving surplus zinc is 
not always the only consideration when galvanizing small articles, 
though many inventors seem to lose sight of the fact. For this 
reason, the cost of production (when considering the merits of a 
machine or process) should always be given considerable attention, 
and cost figures, obtained under actual working conditions and not 
made in round figures from estimates or unconfirmed reports, 
should be secured for careful consideration. 



CHAPTER VIII 

Galvanizing Sheets 

SHEET iron, wire, wire cloth and poultry netting are gal- 
vanized by being passed through the zincing' bath mechani- 
cally, and as the mechanical means employed are so varied 
and complicated we shall not attempt to illustrate them. The 
galvanizing of these materials is carried on principally by large 
manufacturers who produce the finished article from the raw 
material, and the galvanizing is simply one process of manu- 
facture. 

As a brief description of galvanizing sheets by hand may be 
useful to some, we will describe the old hand method in use before 
the introduction of mechanical methods. 

The hand galvanizing of sheet iron requires the use of a kettle 
long enough to accommodate the sheet and deep enough to permit 
of its being dipped in the bath without interfering with the dross 
in the bottom of the kettle : consequently, a kettle for sheets must 
of necessity be not less than 8 feet 6 inches long by 4 feet deep, 
and it should not be less than 18 inches in width, and a better 
width is 2 feet. As it is necessary to pass the sheet into the molten 
metal through a flux of sal ammoniac what is known as a "flux 
guard'^ is employed. This flux guard should be made of T-iron, 
to which an iron plate can be riveted so that when the arrangement 
is placed in the bath the guard eft'ects a longitudinal division of 
the metal. This flux guard should be wide enough to go under 
the metal 2 or 3 inches when the metal is at its lowest working 
height. After a sheet has become thoroughly coated it is pushed 
to the side of the kettle that has not been covered with a sal 
ammoniac flux and withdrawn from the metal with the aid of 
properly shaped tongs attached to a light single block and fall. 
If the pickling and inspection of the sheet has been properly done 
the coating takes place without the usual rinsing or washing 
through the sal ammoniac flux floating on the surface of the 
molten bath; but unless this has been properly done, it will be 
necessary to wash the sheet through the flux until a perfect coat- 
ing has been obtained. 

73 



74 GALVANIZING AND TINNING 

In the hand dipping method of galvanizing sheets, a simple 
arrangement was used that permitted the ojierator to transfer the 
sheet from the side of the l^ettle where it entered the hath to the 
opposite side where it was withdrawn, and also permitted the edge 
of the sheet being lifted, semi-automatically, just high enough out 
of the metal to permit of its being readily seized with the tongs 
used for withdrawing it from the bath. It was the practice in 
some plants to allow the coated sheet to form crystals by cooling 
in the air, after which the sheet was plunged into a bath of cold 
water and dried oil in sawdust. When it was desired to have a 
bright plate without the crystals the sheet was plunged into the 
water immediately after it had been drawn from the molten metal. 
This prevented the formation of crystals and, as stated, produced 
what was known as bright galvanized sheets. 

Among the old English galvanizers it was the practice to carry 
a clean flux of sal ammoniac on the opposite side of the flux guard 
from which the sheet entered. This prevented oxidation and was 
the means of producing a somewhat thinner coating. It was also 
the practice of some operators to cover the metal on the side of 
the flux guard from which the sheet was drawn with foundry sand 
or coke dust. 

Mr. James Davies, an English authority on galvanizing sheets, 
describes in his book, entitled "Galvanized Iron, Its Manufacture 
and Uses," a very practicable and simple mechanical device for 
the galvanizing of sheets. His device consists of a strong square 
iron frame in which two rollers work. The rolls are made of 
hammered forgings and turned. He gives the usual size as 3 feet 
6 inches long by 9 or 10 inches diameter. The frame and rolls 
are suspended from l)ars placed in the bath at such a depth that 
the rolls are completely immersed in the metal, with the center of 
the rolls from 14 to 15 inches below the surface. The rolls have 
a hammered wrought iron pinion on the end of one and two 
wrought iron pinions at the other end, and are driven by another 
wrought iron cog wheel. The driving shaft should have a four- 
cone pulley with a corresponding cone pulley overhead for vary- 
ing the speed according to the thickness of the sheets, as a thin 
sheet takes less time to coat than a thick one. With this arrange- 
ment what is known as a flux box is placed on the entrance side of 
the bath and one on the exit side of the bath. Erom these flux 
boxes guides are arranged which are removed when the day's 



GALVANIZING SHEETS 75 

work is finished. Tlie sheet goes into the flux box in the wet 
state and as it emerges from the flux box on the other side it is 
seized by the operator with a pair of self-acting tongs which are 
attached to a rope running over a pulley. The action of the rolls 
in the bath keep up a constant circulation of the metal, which, in 
a measure, prevents the dross from solidifying. 

In addition to this comparatively simple method of galvanizing 
sheets automatically, we have what is kno-\vn as the "Heathfield's 
Patent Process/' the advantages of which are best described in the 
patentee's own language, which is, in part, as follows: 

"One man and one boy are sufficient to run the machine, and 
their combined labor will turn out far more galvanized sheets per 
day than a much larger number of men can do by any other 
process. 

"The machine will turn out with sufficient lal^or 12 tons or 
more of galvanized sheets assorted, 14 to 30 gauge or thinner, per 
turn of 10^ hours, and with a good dipper will sometimes do as 
much as 11 or 12 tons per turn of sheets assorted 26 to 30 gauge; 
while 8 English tons is a very moderate average in a turn of 10^ 
hours for sheets of these latter thicknesses. 

"The machine will do any thickness from 14 to 30 gauge or 
thinner, any width up to 4 feet (or wider if a large enough ma- 
chine is su23plied) and any required length. 

"As the pot is only 2 feet 8 inches deep, and holds only about 
12 tons of spelter (^inc), the very large output, compared to the 
quantity of spelter in a molten state, reduces the dross made per 
ton of sheet below that made by any other plan ; the pot, of course, 
being pushed to its maximum, and worked night and day. 

"No oxide is made while the machine is at work. 

"The quantity of muriate of ammonia used per ton of sheets is 
very small. Fourteen pounds, or less, will suffice to galvanize one 
ton of sheets, 28 gauge thick, while stronger sheets take propor- 
tionately less. 

"The coke bill is small. If the pot is kept fully at work, six 
tons of ordinary gas coke of fair quality will keep the pot at work 
a week, including firing it on Sundays. 

"The quantity of spelter used per ton of galvanized sheets made 
is greatly reduced, while the appearance of the sheets is much im- 
proved, and they leave the machine ready for use, without any 
subsequent brushing, washing or drying. 



76 GALVANIZING AND TINNING 

"The following are the approximate quantities of spelter de- 
posited on the sheets, in the manufacture of one ton of galvanized 
iron by the Heathiield patent machine; the various gauges being 
calculated at the number of galvanized sheets per ton, which it is 
usual to supply in England: 



16 


18 


20 


24 


26 


28 


30 gauge 


120 


140 


195 


245 


325 


350 


420 pounds 



"In the very light gauges it is possible to use sheets a gauge 
stronger than can be used in the ordinary process, and yet pro- 
duce the same number of galvanized sheets i^ev ton as is customary 
by the old plan. 

"This saves considerably the cost of black sheets on 28, 29 and 
30 gauge galvanized." 

In addition to the Heathfield process we have the Bayliss patent 
process. The patentee makes the following claims for his process : 

"The patentee claims that this method dispenses with a con- 
siderable amount of manual labor. The patentee passes the 
sheets, after being pickled, through a pair of cold rolls upon 
which a stream of water is continually flowing. The object 
of this is to impart a fine smooth surface to the .sheets which 
have been roughened by the pickling process. From the cold 
rolls the sheet passes onwards towards the bath which it en- 
ters through a pair of rolls fixed on the brickwork of the gal- 
vanizing bath. It then passes through a guide fixed below the 
surface of the metal, and finally emerges through a layer of sand 
on the surface. The sheet is then seized by a pair of rolls having 
studs inserted at intervals which meet and grip the sheet. The 
sheet then passes on by means of an endless chain band to a set of 
revolving brushes which brush off any adhering particles of sand.^^ 



CHAPTER IX 

Galvanizing Wire, Netting and Tubes 

WIRE, wire cloth and poultry netting are galvanized prac- 
tically automatically. In galvanizing wire cloth and 
poultry netting it is necessary to divide the molten metal 
longitudinally with a flux guard of the character descrihed for gal- 
vanizing sheets. The side of the hath where the material enters 
should he covered with a heavy flux or sal ammoniac, and the side 
where it leaves the metal should he covered with coke dust to a 







Fig. 35 — Automatic Wire Galvanizing Machine 

depth of several inches. The coke dust must he constantly sprinkled 
with water while the material is passing through it. The best 
means to accomplish this is to have a perforated water pipe of 
the required size constantly discharging water in sufficient quan- 
tities to keep the coke dust on the surface of the metal well moist- 
ened. The operation of drawing the work through the molten 
metal is performed by a revolving drum so constructed as to per- 
mit of the ready removal of the roll of wire cloth or poultry net- 
ting after it is galvanized. Where wire is being galvanized, several 
strands are passed through simultaneously, and the speed varies 
according to the gauge of wire being handled. 

A description of a device that is claimed to be an improvement 

77 



78 GALVANIZING AND TINNING 

for galvanizing wire cloth recently appeared in The Brass World, 
as follows, and it is illustrated by Fig. 35. 

An Improvement in Galvanizing Wire Cloth 

"An improvement in galvanizing wire cloth has been patented 
by George M. Wright. The cloth is drawn from a reel down 
through the bath of molten zinc, contained in an iron kettle. At 
the bottom of the kettle are roller guides, as shown in the illustra- 
tion. The cloth then passes through a mass of charcoal 9. At 
the same time a lateral motion is given the cloth by a device 
shown. The charcoal removes the surplus zinc from the top and 
sides of the wires of the cloth, but on the l^ottom of the meshes it 
fails to brush it off. By giving the cloth a lateral motion, however, 
this surplus zinc on the Ijottom of the mesh wires is scraped oft'." 

The Influence of Galvanizing on the Strength of Wire 

As there are enormous quantities of galvanized wire used, the 
effect of hot galvanizing on the strength of wire may be of interest 
to some, and we cite the folloAving from Tlie Iron Age. 

"At the International Congress of Metallurgy, held at Dussel- 
dorf recently. Dr. Heinrich Winter of Bochum read an elaborate 
paper on tiie above su1)ject. Particularly in mine installations is 
it important to protect the hoisting ropes l)y a suitable rustproof 
covering. Coating with zinc has been found to answer the pur- 
pose admirably, for the protection afforded depends upon the for- 
mation of a couplet in which the zinc of the galvanized iron forms 
the electro positive element and the iron the electro negative, when 
the material is immersed in water or other fluids. The zinc takes 
up oxygen, gradually forming a zinc oxide, while on account of 
the evolution of hydrogen the iron remains inert even if the con- 
tinuity of the zinc coating is slightly broken. 

"In the process of hot galvanizing there is no question, how- 
ever, but that the strength and particularly the resistance to bend- 
ing and torsion are considerably affected, and the purpose of the 
paper in question was to determine the degree of this action. Many 
theories are given regarding the loss of tensile strength. Poor 
material is cited, but tests have shown that even the best of mate- 
rial suffers loss. Again, the steel is supposed to have been 'over- 
drawn,' but microscopic tests do not show signs of this in mate- 
rials losing 38 per cent, of resistance to torsion effects. Finally, 



GALVANIZING WIRE, NETTING AND TUBES 79 

irregularity in the coating of zinc is supposed to change the re- 
sistance to torsion, by obstructing the power applied, in varying 
degree in the test piece. This also will not explain the situation, 
for many wires with uneven coats of zinc showed practically no 
deterioration in this regard. 

How Tests Were Made 

"To study the matter carefully, the first thing was to note 
whatever changes might be produced by the drawing down of the 
billet to wire. Twelve test pieces were therefore cut from the 
material from the original billet down to the actual wire, pickled 
and galvanized, but not annealed. These sections represented the 
various stages through which the material went, and were etched 
by immersion in a copper-ammonium-chloride solution (1:12) 
for one minute each, the copper deposited being carefully wiped 
off with absorbent cotton while under water. The lighter outer 
zone as distinguished from the darker inner zone, showing segrega- 
tion, could be followed plainly through the whole series made from 
this billet. Further etching with an alcoholic solution of picric 
acid (1: 25) for 15 minutes indicated that the grain of the inner 
higher phosphorus zone was larger than the outer one with lower 
phosphorus. The results of the physical tests on the material 
showed the usual phenomena, an increased ultimate strength, with 
brittleness to a point to almost wipe out the power to twist it in 
the final wire before further heat treatment. 

"In order to not disturb the zinc layer in making sections for 
polishing, the wire was first cleaned carefully Avith alcohol and 
ether, placed in a solution of copper potassium cyanide, and a weak 
current applied to coat it with copper. It was then washed with 
alcohol and ether, and finally melted into Eose's alloy, which on 
account of its low melting point gave a perfect protection for the 
galvanizing coat, and yet did not alter the miscrostructure of the 
material. Finishing up the polished sections with a very little 
rouge on parchment paper with a 2 per cent, solution of ammonium 
nitrate for five minutes, thus etching them, gave excellent results. 
With 125 diameters enlargement the makeup of the section is 
plainly shown. A dark band for the zinc, light for copper and 
black for the Eose metal, with lighter color for the steel. A sepa- 
rate band may be distinguished between the iron and the zinc 
coat. 



80 GALVANIZING AND TINNING 

Absorbed Hydrogen Gas Does Damage 

"This material^ it should be remembered, was pickled before 
gah^auizing. Hence many investigators brought back the brittle- 
ness of galvanized steels to an absorbed hydrogen from the acid 
bath. This absorbed gas can, therefore, do considerable damage. 
Further investigations, however, have shown that heating the steel 
up to 250 degrees F. for four hours removes this effect entirely. 
Hence, inasmuch as the microscope does not show any indications 
of an iron hydroxide either there remains only the theory that 
between the zinc and the iron there is a layer of an iron-zinc 
alloy, formed either because the wire was left in the zinc bath too 
long in contact with the zinc, or that the bath was too highly over- 
heated. That such an alloy exists is well known, every galvanizer 
being worried by large amounts of 'dross,' which contains 3 to 5 
per cent, iron, and is a very brittle material. On the other hand, 
in order to get the zinc coat to stick to the iron, it is necessary 
that such an alloy be made with the iron, the composition varying 
from high zinc at the contact to no zinc a little distance into the 
iron, as was clearly shown by Sherard Cowper-Coles. 

"A study of the structure of the material before galvanizing 
shows that where this is large grained and easily to be penetrated, 
much zinc gets in. Even where the microscope does not show the 
layer of the zinc-iron alloy, it is undoubtedly there as a very fine 
one, and depending upon the extent of this layer will be found 
the phenomenon of loss in power to bend and twist when taken in 
coimection with the change in structure through the heat treat- 
ment. It is well known that with soft steels the elasticity is 
changed with temperatures ss low as 750 degrees F., but it also 
takes some time to do this. Hard drawn steel would consequently 
become softer by remaining in the bath longer, but this gain will 
quickly be offset by the formation of a heavier layer of iron-zinc 
alloy. 

"The conclusion of the paper is that the wire industry is per- 
fectly capal)le of furnishing galvanized wire which has not suf- 
fered seriously as to its physical j^ropcrties, this being a question 
of proper practice in regard to removal of damage done by pick- 
ling, and proper bath temperature and time of the wire remaining 
in it. It is, therefore, necessary to treat the wire before galvanizing 
to remove the hydrogen absorbed and to regulate the temperature 
of the zinc bath between close limits. The latter is not easy, as 



GALVANIZING WIRE, NETTING AND TUBES 81 

there are difFiciiltics in pyroinetry and also in the proper firing 
where many wires are passed through constantly with consequent 
irregular lowering of the temperature." 

The Automatic Galvanizing of Tubes 

Iron and steel pipe and tubes are hot galvanized in large quan- 
tities annually, and large tube manufacturers have, of course, 
adopted mechanical means as far as possible for handling their 
product through the galvanizing process. Many ingenious de- 
vices have been invented and many of them are patented. Such 
a device was illustrated and described in The Iron Age recently 
as follows : 

"An arrangement that has been in successful operation for the 
last three years at Laurahiitte, Upper Silesia, for the hot galvaniz- 
ing of tubes, is described I)y Engineer G. Buchert of Laurahiitte. 
Fig. 36 shows the details. The tube a is drawn out at one end of 
the zinc bath & and passed through the arrangement c for remov- 
ing the excess spelter from the outside and smoothing the surface. 
It is gripped in tongs attached to a specially built transverse piece 
and by means of the two endless chains d is carried up the incline 
e and along the upper track /. After the lower end of the tube 
has passed through the cleaning arrangement it falls on the clean- 
ing grate g, and automatically cleans itself by striking against the 
bars of the grate, so that all the excess spelter on the inside of the 
tube falls down and- collects in the space h underneath the grate. 

"After the tube has reached the end of the grate it comes on 
to the inclined bench I. The position of this bench when at rest 
is horizontal, slightly higher than the Avater bosh m. (See end 
view.) The falling of the bench to the inclined position is brought 
about by the wire cable n. This is fastened to the traveling piece o, 
which is carried along the upper track by the tongs (holding the 
tube) to the automatic release p. The moment the tongs are 
opened the bench I carrying the tube takes its original horizontal 
position. By means of levers, the bench is inclined and the tube 
rolls of itself into the water bosh m. It is raised from here by the 
revolving shaft q with its star-like arms r, and rolls down the 
skids into a car, properly galvanized and cooled. The tongs and 
cross piece fall down the incline s on a traveling belt t, and are 
carried back to the starting place, where a new tube is taken, 
gripped and started on its way by hand. 



82 



GALVANIZING AND TINNING 




Pm 



OALVANTZIXG WIRE, NETTING AND TUBES 83 

"As oompared with hand galvanizing, the apparatus has shown a 
saving in wages of 33^ per cent, and in spelter of 0.8 per cent, of 
the total weight of tubes to be treated. Under German conditions 
this amounts to $1.48 per metric ton of finished tubes. A special 
crane for holding and agitating the tubes during pickling is also 
briefly described, which lias proved very successful." 



CHAPTER X 
By-Products of the Hot Galvanizing Process 

THREE by-produets are produced in the process of hot gal- 
vanizing. They are known by the trade terms of "Hard 
Zinc Dross," "Sal Ammoniac Skimmings" and "Zinc 
Ashes," sometimes called "Dry Zinc Skimmings," and a brief de- 
scription of each is given in order. 

These materials are bought by all the principal scrap metal deal- 
ers, who, as a rule, can be depended upon for fair business deal- 
ings. There are exceptions, however, and for this reason sellers 
should never dispose of galvanizing by-j^roducts by sample nor 
allow the word sample, or reference to any particular grade of 
quality, to be used in the terms of sale. The buyer may be per- 
mitted to take samples of the materials from the bulk as he 
chooses, but only at his own risk. Each lot should be sold on its 
merits as it stands without any representations as to quality and 
absolutely without recourse, except in the matter of weights, which, 
of course, should be as unquestionably accurate as possible. We 
have learned through exj^erience that failure to take these pre- 
cautions may lead to a great deal of trouble and expense. 

Prices vary with the price of Prime AVestern Spelter, and the 
quotations made are usually based on the price of this metal, and 
the terms of payment in the sale of these materials are nearly 
always cash. 

Workmen cannot be too careful in the removal of by-products 
from the galvanizing bath, as every pound of good zinc removed 
unnecessarily represents a direct loss, and it is a fact that gal- 
vanizing employees as a rule are inclined to be careless with and 
slow to appreciate the value of materials which they use. By- 
products are valuable, and should be treated and stored accord- 
ingly. It is economy to place a thoroughly competent and con- 
scientious man in charge of a galvanizing plant even at what 
might seem a high price. The man who is satisfied with the small- 
est salary is not necessarily the cheapest man, and the fact should 
not be lost sight of that a few dollars saved on the pay-roll may 

84 



BY-PRODUCTS OF THE HOT GALVANIZING PROCESS 8i> 

easily he more than offset hy losses due to iiieoiiipeteney and waste- 
ful carelessness of a foreman or those workinti,- under liim. 

The question often arises as to wlietlier it is advisable for the 
individual galvanizer to attempt the recovery of his own by- 
products. The reclaiming and utilization of these so-called waste 
products has received the attention of scientific men in recent 
years, and as previously stated, have, through scientific investiga- 
tions and experiments, heen made to yield high values. 

Commercially practical methods for the economical treatment 
and use of drosses and skimmings on a large scale have heen de- 
veloped with the result that galvanizers can now secure high prices 
for materials which were formerly consigned to the dump as waste 
products, and it is douhtful if they can realize as great returns 
by the treatment of their own by-products as by selling them at 
prevailing prices to the large buyers who make a specialty of 
handling these materials. 

Zinc Dross 

Zinc in a molten state wall alloy with iron so that iron sub- 
merged in it will begin to dissolve as soon as it becomes as hot as 
the zinc bath. The addition of only a small percentage (as little 
as 3 or 4%) of iron to the bath will form an alloy of zinc and 
iron called zinc dross, that is of greater specific gravity than zinc 
itself. 

This dross in galvanizing is formed principally by the con- 
tinued washing away of the articles which are being galvanized, 
although a consideral)le amount is formed by the action of the 
zinc on the inside of the kettle, as evidenced by the gradual eat- 
ing away of galvanizing kettles from the inside nntil they are 
eaten completely through, necessitating the installation of a new 
kettle, and if by accident or design the kettle is run at a high 
heat, dross will form very fast. As the dross forms it settles to 
the bottom of the kettle and becomes hard. When the accumula- 
tion has reached a point where it interferes with the work it must 
be removed. This is easily done with the use of a proper tool made 
for that purpose and called a dross scoop. The handle of the 
scoop should be about twice the length of the kettle unless the 
kettle is of a size requiring the use of tackle in drossing it. The 
scoop should be well perforated with holes not less than V' in 
diameter to allow the clear metal to flow back into the kettle, and 



86 GALVANIZING AND TINNING 

care should be taken to keep these perforations always open and 
unobstructed. 

Before commencing to dross the kettle, i.e., to remove the dross, 
skim all the flux from the surface of the metal with a perforated 
skimmer, and if it is in good condition save it for future use. If 
this flux is broken up when cold and placed carefully back on the 
surface of the zinc it will soon melt to its former consistency. A 
perforated skimmer for removing sal ammoniac flux and zinc ashes 
is shown in Fig. 25 and is designated F. 

When drossing do not stir or roll the bath unnecessarily in forc- 
ing the scoop into the hardened mass. Force the scoop gently into 
the dross and when satisfied that it is full raise it out of the metal 
by resting the handle on the end of the kettle to get a leverage. 
Let the scoop remain supported on a bar over the kettle until all 
the liquid metal has drained back. Dross hardens very rapidly 
when exposed to the air, and no more time than necessary to allow 
as much good metal as possible to drip back into the kettle should 
be consumed before getting the dross into the dross pans. If the 
handle of the scoop is jarred l)y blows from a hammer or bar of 
iron more of the clear metal will separate from the dross than if 
this was not done, and the mass of dross will also drain much 
more freely if cut down through several times with a flat iron 
shovel. As soon as clear metal ceases to drip, dump the dross 
while still in a semi-fluid state into cast iron pans or molds made 
for the purpose and about 2" deep, 15" long and 9" wide inside. 
The dross, while still hot, should be worked or molded into the 
pans and smoothed off on top with a shovel. When the dross 
hardens in the molds dump them and you have the commercial 
Hard Zinc Dross. 

If there should be a large amount of dross in the kettle at a 
time when it is desired to allow the fires to go completely out it 
should be removed. If allowed to cool with a large amount of 
dross lying in the bottom the result will most likely be a burst 
kettle. 

The loss caused by the formation of dross is quite large even 
with an experieiiced man in charge of a kettle, but the amount 
of dross made is greatly increased by failure in keeping the metal 
at a temperature which will not injure it; also by allowing work 
to be lost in the kettle or by immersing work in the bath that has 
not been properly prepared. 



BY-PRODUCTS OF THE HOT GALVANIZING PROCESS 87 

Running Over or "Sweating" Zinc Dross 

We are often asked whether it will pay the small galvanizer to 
try to recover the good zinc from his dross, and if so, how best to 
accomplish the desired results. It formerly was the practice of 
most concerns doing galvanizing to rmi over, or, as it is termed, 
"sweat" their dross, but conditions which formerly made this profit- 
able have changed materially in the last few years. At the time 
of the first issue of "Galvanizing and Tinning" the very best zinc 
dross could be bought at from 25 to 35% of the price of spelter. 
To-day the most inferior grades readily bring from 50 to 60%, and 
some of the better grades as high as 80% of the price of the best 
quality of zinc. 



Fig. 37 — Dross Sweating Fuknace 

Without entering into any further discussion regarding the ad- 
visability of attempting the recovery of zinc dross, we reproduce 
the illustrations of apparatus for "sweating" dross that appeared 
in the first issue of "Galvanizing and Tinning." In Fig. 37 we 
give a perspective view of the kettle and brick work. Fig. 38 is 
a top view. Fig. 39 is a vertical section of Fig. 38 at A A, and 
Fig. 40 is a horizontal section of Fig. 39 at the grate line B B. 
The kettle and casting details for bricking in are shown in Fig. 41. 
This arrangement is so simple that we do not think it necessary to 
describe it in detail. 



8^ GALVANIZING AND TINNINC 

A kettle 30" in diameter and 20" deep will answer the purpose 
very well, and should be made of cast iron, with bottom about 1^" 
thick. 




-A 




Fig. 38 — Plan of Furnace 



Fig. 39 — Vertical Section of 
Furnace at A-A Fig. 38 




■Sect/on B-B 

Fig. 40 — Plan of Furnace at Grate Line 

To separate the good metal from the dross, first melt up about 
6 or 8 inches of lead in the bottom of the kettle and then put in 
the dross. Bring the dross to a temperature that will cause it to 
have rather a dark blue color, or to a point where the pyrometer 
will register about 1050 degrees. When this is accomplished stir 
the mass with a long-handled ladle for about one-half hour, and 
then allow it to settle. When the mass has settled the lead will 



BY-PRODUCTS OF THE HOT GALVANIZING PROCESS 



m 



be at tlio liottom, tiip dross will lie on thi' load and iho clear metal 
will 1)0 at tlio top, where it can be l)ailed out into pans. The stir- 
ring may l)c repeated once or twice after each bailing operation. 
After all the clear metal availal)le has been extracted, remove the 
dross and \n\t it into pans or molds as when first taken from the 
galvanizino- kettle. 




Fig. 41 — Castings for Dross Sweating Furnace 



Sal Ammoniac Skimmings 

This is the trade term for the sal ammoniac flux used, on the 
top of the galvanizing kettle when its usefulness as such has 
l^assed. The thick dirty portion of the flux must be removed from 
time to time as necessary and should be placed in sheet iron pans 
of convenient size to cool, when it will be the commercial Sal 
Ammoniac Skimmings, and should be stored in a dry place. In 
a plant ojoerated for small castings, forgings and similar work this 
skimming is usually done twice daily, once the first thing in the 
morning and once before starting m the afternoon. 

Too much care cannot be used, in skimming the spent flux from 
the galvanizing bath, as a considerable amount of zinc can be 
carried o£E in the flux by carelessness without its being noticed or 
suspected, and may be the means of quite a loss. A perforated 
skimmer, shown in Fig. 25 and designated P. should always be 
used, and it should be kept clean. The perforations should be 
sufficiently large to permit free exit of metal, about ^" diameter, 
and the handle of the skimmer should be tapped on the edge of the 



90 GALVANIZING AND TINNING 

kettle while filled with hot flux to shake out as much of the fre6 
metal as jDossible. 

Sal Ammoniac Skimmings should never be mixed with Zinc 
Ashes, as the value of both will be considerably reduced by so 
doing. Each should be skimmed from the bath into a separate 
receptacle, stored separately and plainly marked when packed for 
shipment. 

While several methods of treatment for reclaiming the wastes 
of Sal Ammoniac Skimmings have been developed, we do not con- 
sider it economical for tlie individual galvanizer to attempt their 
recovery on a necessarily small scale for reasons previously stated. 
In a 23lant having several kettles in operation considerable zinc 
can be recovered from Sal Ammoniac Skimmings with little ex- 
pense by remelting them in a large mass. This can best be done 
after dressing when the surface of the zinc is low down in the 
kettle. Put several days' accumulation of skimmings, which have 
been kept in a dry j)lace, ijito the kettle at once, which, when 
melted, should be several inches deep on the top of the metal. 
Stir this mass well with a poker or skinmier and then skim it off 
into flux pans, taking first the lighter top portions, and being care- 
ful to dip the skimmer through into the molten zinc no more than 
necessary. 

Large lots of Sal Amnionic Skimmings are often shipped loose 
in bulk, while small consignments are usually forwarded in casks 
or barrels. 

Zinc Ashes 

The name Zinc Ashes is the trade term for what is really zinc 
oxide, and which in the galvanizing process accumulates on the 
bare surface of the molten zinc. Zinc Ashes are formed by con- 
tinually skimming the surface of the liath clean for the withdrawal 
of work and by the melting up of new spelter after drossing. It 
also collects when the bath is lying idle if it is in a molten state, 
as on Sundays and holidays. 

Before removing Zinc Ashes from the kettle a little white sal 
ammoniac should be sprinkled over and well stirred into them with 
a poker or skimmer. This will be found of great assistance in re- 
ducing the particles of metallic zinc to a molten state. 

Plenty of time and care should be used in skimming, as small 
drops of zinc remaining suspended in the hot ashes are very hard 
to shake out, and carelessness will greatly increase the losses. 



BY-PRODUCTS OF THE HOT GALVANIZING PROCESS 01 

It is good practice to screen Zinc Ashes through a No. 6 or 
No. 8 mesh riddle, either by hand or machine, before packing them 
for the market, throwing out all foreign material. A surprising 
amount of zinc can be recovered in this way, which can be easily 
remelted in the galvanizing bath. 

Any attempt at reclaiming the fine ashes does not pay, as the 
reduction of zinc oxide is not at present commercially practical 
for the small operator. These ashes or oxides are largely used by 
paint manufacturers, however, and they find a ready sale in the 
scrap metal market. 

Zinc ashes are usually packed for shipment in bags or barrels, 
and should always be stored in a dry place. 



CHAPTER XI 

Replacing Old Galvanizing Kettles 

GALVANIZING kettles are good for service until they begin 
to leak badly or have become so warped or distorted that 
they cannot be operated satisfactorily. The life of a kettle 
ranges from a few days or weeks to several yearS;, depending on the 
class of work handled, and whether it has had careful and intelli- 
gent operation. Comparatively new kettles sometimes develop a 
leak through some defect in the steel sheet from which they are 
made. If such kettles are in good condition otherwise it may pay 
to bail the molten zinc out to a j^oint below the leak and repair 
it, either by rivetting on a patch or by welding with electricity, 
oxy acetylene gas or other method that seems most advisable or 
economical. 

If an old kettle which seems to be generally thin and worn 
starts to leak it is usually economy to tear it out and replace at 
once Avith a new one. If a successful attempt is made to stop a leak 
in an old kettle of this kind it will more than likely start to leak in 
other places within a very short time and your trouljle and ex- 
pense will be of little avail. 

When a kettle, whether old or new, starts to leak no time should 
be lost in bailing the molten metal out to a point below the leak, 
always removing as much dross as possible before taking out the 
clear metal. At this point it can l)e decided whether or not to 
try and repair the kettle and if not, continue the l^ailing operation 
until the kettle is empty, always removing the dross first. When 
bailing out an old kettle do not let the fires cool off too much, 
thereby allowing the zinc or dross to congeal on the sides, as you 
may have consideral)le difficulty in removing it. 

When an old kettle, especially a large one, suddenly starts to 
leak badly it is often advisal:)le to secure considerable extra help 
in order to remove the dross and metal quickly, thus preventing 
the molten zinc from running into ash pits or elsewhere and cool- 
ing in such a Avay that it cannot be easily recovered or handled for 
re-melting. A little extra expense in the matter of labor employed 
at such a time can easily result in a substantial saving later on. 

92 



REPLACING OLD GALVANIZING KETTLES 93 

An ordinary iron muldcr's ladle with an iroii handle makes an 
excellent tool for hailing out a galvanizing kettle, and several 
should he kept on hand ready for use if they are liahle to he re- 
quired in sueli an emergency. 

After an old kettle has been hailed out as clean as possihle draw 
the fires and wet it down with water to hasten the cooling ofE 
process if necessary, after which remove carefully all holts, nuts, 
castings and other iron work for use again. The brick work can 
then be torn down to the foundation and the old kettle removed, 
after which the new kettle may be set up on the same foundation, 
filled with zinc and heated up the same as any new kettle, instruc- 
tions for which are given on pages 20 to 26 and 66 and 67. 



CHAPTER XII 

The Schoop Metal Spray Process 

ONE of the great metallurgical problems of the day has been 
to produce a non-corrosive surface on iron and steel, the 
indispensable but vulnerable materials of engineering con- 
struction, without affecting the physical properties of these metals 
or the shape or usefulness of the object treated. 

There are demands in the arts for a method which will take the 
process to the work or to any part of it, and will secure the quick 
deposition on any coherent object, whether metallic or not, of any 
desired metal or alloy in any quantity, however minute. 

This is the ideal metal coating process. Inventors have labored 
over the problem for many years but commercial results have not 
been developed until recently because of the lack of economy in 
the earlier forms of apparatus. 

The overlaying of iron and steel for temporary effect with non- 
metallic substances, such as paints, enamel, japan, and varnish, has 
been the mechanical method necessarily followed hitherto for the 
great bulk of metal objects and structures and the renewal and 
maintenance of such protections involves enormous outlays. It is 
the object of this chapter to describe the latest mechanical process 
for depositing electro-positive metals, such as tin and zinc, on iron 
and steel. Incidentally, the method permits of depositing many 
other metals and alloys on coherent bodies whether metallic or not. 

The Process takes its name from M. U. Schoop, an engineer of 
Zurich, who, in collaboration with other inventors, made the metal 
spray an effective coating agent. In the Schoop Process, the 
United States patents for which have just been issued, the coating 
metal adheres to the object chiefly by mechanical union. The 
metal is discharged in hot impalpable particles moving with high 
velocity, and these when directed upon a prepared object penetrate 
the pores of the latter while the spray is still plastic. The coating 
metal thus dovetails itself into the superficial pores of the object 
and does so in the presence of reducing gas, which prevents oxi- 
dation at the junction of the metals. 

The progress of invention on metal spraying has been chiefly 

94 



THE SCHOOP METAL SPRAY PROCESS 95 

directed toward making the metallic particles as small and as hot 
as possihle and to avoiding oxidation. 

In 1902 Thurston, United States No. 706,701, was granted a 
patent for impacting, with unignited gas, metal in the form of 
dust upon a metallic base. His apparatus was not practical and no 
commercial results were obtained. 

Within the past year four United States patents have been issued 
which embrace all the important steps since Thurston's invention. 

Schoop, United States No. 1,128,058, invented a process for pro- 
ducing a fine spray from either molten or solid metal and also for 
producing separable metallic coatings or copies of the objects 
sprayed upon ; this was known as the liquid metal spraying process. 

Schoop, United States No. 1,128,059, later invented a process for 
projecting finely divided unmolten metal particles on to a surface, 
using an ignited gas and metal in the form of dust like Thurston. 
This was known as the metal dust spraying process. 

Very soon afterward Morf, United States No. 1,128,175, in- 
vented a process for melting, atomizing and projecting, practically 
simultaneously, solid metal and particularly metal in the form of 
wire. This was known as the metal wire spraying process. 

At the same time Morf, United States No. 1,100,602, invented 
a successful apparatus (known as a "Pistol"), for effecting this 
process. 

These inventions above outlined form the basis of the Schoop 
Metal Spray Process_ as it is now operated in the United States. 
The present chapter is wholly concerned with the apparatus used 
for tinning and galvanizing by this method and with the applica- 
tions possible. 

The evolution of the apparatus has been interesting. The liquid 
metal process involved a large non-portable reservoir of hot metal 
weighing with the auxiliary parts over a ton; the metal dust ap- 
paratus weighed over a hundred pounds, while the "Pistol" of 
to-day weighs less than four pounds. 

Figures A, B, and C show the three forms through which the 
apparatus has passed. 

In the apparatus represented by Fig. A, a melted metal is allowed 
to run continuously from the reservoir "R" through a broad noz- 
zle "N," where it is broken up and swept away by a violent cur- 
rent of heated gas "G," issuing under regulated pressure from 
containers "C" and reheated in its passage at "H." The expansion 



96 



GALVANIZING AND TINNING 



of the gas chills the molten particles and forms a rapidly moving 
spray or fog of metal which impacts n|)on any ol)ject placed in its 
path and plates it. 

Any metal fusible imder the conditions of the apparatus can be 
used and owing to the low temperature of the fog, it is possible to 
plate very delicate or easily comljustible objects, as well as metal 
articles. 




Fig. a — First Type of IMetal Spray Apparatus 



Aluminum plating, which could not be obtained by fusion or 
electrolysis on account of its ready oxidation, was easily obtained 
by the Schooj) Process. 

The obvious objections to such an apparatus were lack of por- 
tability and the expense of melting and keeping fluid most of the 
metals in the unavoidable intervals of spraying. The result was 
that only the more fusible metals, zinc and tin, were used where 
spraying on a continuous scale was possible and the liquid metal 
apparatus was never reduced to economical practice. It was ob- 
served with this apparatus, however, that the particles were not 
actually molten at the moment of impact and this suggested the 
next step. 

Fig, B represents the second form of apparatus in which -porta- 
bility was secured and the metal particles to be sprayed were pre- 
pared in advance. Powdered metals in a very fine state of division 
have many of the characteristics of a liquid. Their fine particles 
mix with one another like drops, they spread with facility and 
unite under the influence of very little force. 

The metal powder in the container "C" is entrained in an air 



THE SCHOOP METAL SPRAY PROCESS 



97 




Fig. B — Second Type, Portable Metal Spray Apparatus 



98 



GALVANIZING AND TINNING 



blast "A," heated in the flame of a blast pipe "B" and projected 
with high velocity. The gas is burned at "A" and the supply of 
air is regulated at "S" to obtain complete combustion. 




Fig. C — Third Type or Metal Spray Pistol 

It was found that the anticipations from the use of the first 
apparatus were correct and that metal particles projected in a 




Fig. D — Detail of Metal Spray Pistol Nozzle 



pasty condition produced plating as before. Metal powders, how- 
ever, are very costly. Most of them tend to oxidize rapidly and 
the use of this apparatus was practically restricted to zinc on that 



THE SCHOOP METAL SPRAY PROCESS 



99 



account. The zinc is a by-product of Zinc Smelteries and is readily 
applied by the simple apparatus known as the "Cyclone/' which 
has just been described. It is still the most economical method of 
producing a Schoop coating of zinc. 

Inventors set themselves to overcome both the chemical and 



Mixed Gas 
.Passage of Burner 



! Inner Nozzle fhctf 
guides wire 



Wire 
Guide 




Connecfion for 
Plixed Gases ' 



Fig. E — Section Showing Detail of Constkuction of Pistol 

economic difficulties with other metals including tin, viz, : to dis- 
pense with mass melting and dust preparation and to secure in- 
stant and simultaneous melting, and pulverization, and control 
with a handy, economical appliance. The result was the ingenious 
instrument known as the "Pistol," which is shown in Fig. C. 

The principle (Fig. D) consists in feeding a fine wire "W" of 
any metal into a reducing flame zone "Z" at such a constant speed 
that the end of the wire "E" remains stationary, its melting rate 
being exactly equal to the rate of feed. Under such conditions 
the wire end melts a drop at a time and each drop at the instant 
of formation is struck a violent blow by an air blast "A." 

The resulting fog or spray of fine particles into which the drops 



100 GALVANIZING AND TINNING 

are divided takes the form of a diverging cone "C" with a core 
of reducing gas "G" in which the particles are entrained, and a 
surrounding sheath of air ''A," which is rapidly expanding and 
cooling. Any suitably prepared object placed in the path of this 
metallic spray is plated through impact without undue elevation 
of temperature. 

Pig. E is a section of the commercial spraying pistol now in use. 
The principal parts of the pistol consist of an outer casing "A," 
cast of aluminum, with a central downward projecting tube form- 
ing a handle, a wire feed mechanism mounted entirely upon the 
cover "B," of the turbine chamber, the turbine "C," actuating the 
wire feed mechanism, gas, air and wire nozzles mounted upon the 
outer casing held in position by a hand nut "D," and a removable 
cover "P," which completes the enclosure of the outer casing. 

Gas and air ducts are drilled in the outer casing, the flow con- 
trolled by the tapered valve "¥" provided with a handle "G." 

The wire feed mechanism is actuated by a turbine "C" mounted 
on a vertical shaft running in ball bearings; a worm is cut in the 
upper end of the vertical shaft and drives by worm wheels the 
horizontal shafts "W and "0", which are provided with worms in 
turn driving the worm wheels "P" and "Q." 

The worms "P" and "Q" are provided with slots to engage the 
projecting lugs of the lower feed wheel "E." The upper feed 
wheel "S" mounted in the pivoted frame "T" is provided with 
shrouds controlling the position of the lower feed wheel "E." The 
lower feed wheel can be engaged in either work "P" or "Q" by 
raising a clip "I" shifting laterally in either direction and locked 
in by the opposite clip. The shift can be readily made by allowing 
the mechanism to run slowly by a slight opening of the starting 
valve. 

Pressure is applied to the feed wheels through the pivoted frame 
"T" by a coiled spring, and controlled by the operator by means of 
the release lever "K." 

The final adjustment of the wire feed is controlled by the needle 
valve "M." The turbine and shaft complete is assembled in the 
outer case and properly adjusted independently of other mecha- 
nism. 

The wire feed is entirely assembled on the turbine cover "D'* 
and when properly adjusted, secured in position. The wire nozzle 



THE SCHOOP METAL SPRAY PROCESS 101 

base ''U" provides an adjustment for position of wire and gas no;^- 
zles, and is seeured in position by a headless set screw. 

The upper end of the stem of the turbine cover is provided with 
an annular groove, which is engsiged by the spring loop "Y" and 
secures the removable cover "E" of the case. Loop "V" provides 
a means for hanging the pistol on a conveniently located hook. 

The Operation of the Pistol 

The. gas and l)last nozzle faces, "B" and "C," are securely 
clamped to form gas tight joints by tightening the hand nut "D." 
The end of the central or wire nozzle is then .015" inside the gas 
nozzle and the stationary melting point of the wire is .03" inside 
the air blast nozzle. The wire diameter used is from .0319" to 
.0375", except zinc and tin, which are used in larger sizes, owing to 
their rapidity of melting. 

The feed gears having been set in mesh at the approximate speed 
required for the wire selected, the air alone is turned on and the 
speed tested with a short length of wire. Adjustment, if neces- 
sary, is made by the needle valve, which modifies the speed two 
feet per minute plus or minus. 

The end of the wire reel is then threaded through the stock 
receiving tube, . between the gripping feed rolls and into the cen- 
tral wire nozzle and the fuel gas pressures from the containers are 
adjusted l3y the reducing valves and gauges thereon to the tabular 
requirements for the metal to l)e sprayed. The pressures of the 
fuel gases seldom -rise above one atmosphere and hydrogen or Blau 
gas are the reducing gases usually emploj'ed. This gas is now 
admitted by slightly opening the starting valve and when ignited 
with a match burns quietly as a pilot light. 

The starting valve is then opened up full and oxygen is admitted 
gradually till the flame zone is established. All 1mck-firing is 
avoided by keeping the reducing gas always in excess of the oxy- 
gen, the ratio l)eing three or four to one. The above movcment:- 
are made in rapid succession on a light instrument which can be 
held in one, hand and the spray is started up the moment the con- 
stant melting position of the wire is reached. 

The spray so established is essentially a metal plating air- 
brush of which the diameter 5" from the pistol end is ab.out 2". 
Objects to be plated are operated upon by pointing the pistol nor- 
mally to the surface to be coated at any moment at about five (5) 



102 GALVANIZING AND TINNING 

inches distance and traversing the pistol across tlie surface with a 
regular motion. 

A single coating is al30ut .001" thick. The operator's vision 
easily guides him in distinguishing between the coated and un- 
coated portions and also between a first and second coat. 

Two thousandths of an inch well impacted upon a surface are 
just as effective as a much greater thickness and of course unneces- 
sary sprayed metal increases the cost, as the latter is directly pro- 
portional to the thickness. 

Not only on the score of economy but also to preserve tough- 
ness the coating should l^e of minimum tliickness, for the anvil 
action of the metallic spray on a solid metal object is lost above 
a few thousandths of an inch thickness and a process of cold 
working follows which produces a brittle scale readily de- 
tacliable. 

In i^ractice this matter is easily regulated. Fig. C shows 
the pistol held in the hand ready for action Avith the wire thread 
in position. Fig. P shoAvs the pistol applied to coat a wooden 
pattern for protection with tin. Gas bombs with fittings and air 
at 40 pounds 23ressure are tlie only requisites besides the "Pistol" 
and its hose connections for plating non-metallic objects such as 
wood, stone, paper, cement, cloth, etc. All metallic surfaces should 
have tlie scale cleaned off and their ^^ores opened by preliminary 
sand-blasting. 

It will be seen from the taljles appended that .001" thickness, one 
square foot in area, of the common metals can l)e sprayed for a 
small sum. The total cost is five cents per square foot for tin and 
tAvo cents per square foot for zinc. 

Various theories have been offered to account for the plating 
properties of the Metal Spray, but it is believed by those putting it 
to practical use that, except in the fcAV cases where the impacted 
metals have a chemical afPmity, the action of the spray is jourely 
mechanical and restricted to superficial pores of the object. 

Metal Spraying is essentially a kinetic energy process and the 
"Pistol" is practically a rapid fire gun which manufactures its own 
ammunition automatically from a reel of wire and discharges an 
infinite number of projectiles which im|)act themselves in the ex- 
posed pores of any object five inches aAvay. In the zinc dust 
"Cyclone" apparatus the size of the projected particle is predeter- 
mined, but the action at the object is identical Avith that of the 



THE SCHOOP METAL SPRAY PROCESS 



103 



'Tistol." In either case with proper preparation of clean, open 
surfaces a durahle, adherent, protective coating is attained. 

In general, the applications of the Metal Spray Process may he 
divided into five groups, namely, protective coatings; honding or 




Fig. F — Method of Using Pistol in Spraying 

junction coatings; electrical coatings; decorative coatings; and de- 
tachable coatings or copies of the objects. 

Protective coatings on steel or iron may be either original coat- 
ings of the whole of an object or structure, or they may be confined 
to any part of it, or they may be merely local applications with the 



104 GALVANIZING AND TINNING 

"Pistor" or '^'Cyclone"' apparatus to repair damage or wear to a 
coating of tin or zinc made by another process. The repair of the 
troublesome defects found on many galvanized and tinned sheets, 
and leading to their rejection, is an application of this process 
which is made only through the possibility of applying tin or zinc 
to any area, however small, and confining it to that area. An- 
other application for the same cause is the filling up of pin holes 
in expensive machine castings, such as printing rolls, etc., which 
would otherwise be a complete loss. 

Many engineering structures used in the arts, such as steel and 
iron tanks, bridges, girders, and machinery of all descriptions, cor- 
rode rapidly, jDarticularly at joints, especially if exposed to atmos- 
phere or liquids. It is not possible to plate such structures by any 
other coating method than the Schoop Process. In such cases 
tin or zinc may be applied from dust or wire form on all seams and 
joints or all over the structure, surfaces having been previously 
cleaned by a light sand-blasting. This treatment can be made on 
the parts of individual memljers at the shops or in the field by 
jDortable cyclone and compressor outfits wherever the nozzle of the 
apparatus can be pointed normally to any surface. Proper initial 
treatment of this kind or in the field during erection dispenses with 
all need for repeated painting. 

Laundry machinery, milking machinery, dairy utensils, water 
heaters, and similar appliances subject to corrosion can be pro- 
tected against decay due to electrolysis by sprayed deposits of zinc 
suitably located. The Schoop coatings do not compete in cost with, 
the ordinary tinning or galvanizing applied to tonnage goods and 
purely temporary in its efi^ects. From the table appended, how- 
ever, showing the data of gas consumption and total cost of spray- 
ing a square foot .001" thick of all the commoner metals, it will 
be seen that tin and zinc can be applied effectively for 21/4 cents 
per square foot ; where zinc dust is applied by the "cyclone" appa- 
ratus it can be done for II/2 cents per square foot. 



THE SCHOOP METAL SPRAY PROCESS 



105 



o o S c 



' o j; o 



<-< iXi CO — ' I^ 00 -— 1 CO 
-f (M "O t^ Ol O O CO 
(M OI Ol Ol ^-< CO CC O 
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CHAPTER XIII 

Tinning Malleable Iron Castings, Wrought Iron and 

Steel 

TO SIMPLY give articles of malleable and wrought iron a 
coating of tin is a comparatively easy process to master, 
but the tinning of certain classes of hardware has reached 
a high state of perfection, and to tin saddlery hardware and table 
cutlery requires considerable skill. The methods employed to do 
the work vary greatly in different establishments, and the degree 
of perfection attained is equally varied. Work that is tinned in 
an indifferent and slovenly manner is not necessarily done cheaply, 
as the metal wasted on an article that is roughly and imperfectly 
coated may be of more value than the slight saving in labor cost 
obtained by rushing the work through without giving proper at- 
tention to the applying of a light and even coating. The high 
price of pig tin makes the material cost of tinning much more 
than the labor cost. The use of care in bringing the finished ar- 
ticles out free from surplus tin not only adds greatly to the com- 
mercial appearance ol: the goods, but materially decreases the cost 
of the work. Tha most economical result is obtained by careful 
attention to tbe h?at of the tinning bath and to the skillful hand- 
ling of the articles duriiig their removal from it and before they 
are cooled. If the tin is not hot enough the articles will be heavily 
coated, and it will cool on the work bunchy and wavy. Tin when 
heated above a certain limit also causes a rough and uneven appear- 
ance of the Avork, injures its color and destroys the luster. The 
use of a good pyrometer in a tinning bath is a great help to the 
operator in maintaining a proper and uniform heat of the tin. 
Care in keeping the tin free from dross or slag is an important 
point in obtaining perfect work and will be referred to in its 
proper place. 

Plant and Equipment 

When installing a tinning plant convenient arrangement for 
handling the work should be given all the consideration possible, 
and the operator will find it a great help toward making his work 

106 



TINNING MALLEABLE IRON CASTINGS, WROUGHT IRON 107 

easy, as well as efficient, if he will study to improve methods and 
tools employed in handling the various articles that come to him 
for tinning. 

While it is our purpose to treat the subject of tinning in a man- 
ner that will enable a novice to make a successful beginning, the 
best results (;an, of course, only be reached by actual experience. 
With the principles and requisites necessary to perfect results well 
understood no trouble should be experienced by one of average 
mechanical ability in mastering the business. 

To make the different ojjerations of preparing and tinning ar- 
ticles of malleable iron, wrought iron and steel easily understood, 
we shall treat each operation separately. 

While the illustrations we give will serve as a general guide in 
equipping a plant, it docs not follow that they cannot be changed 
to suit local conditions. It would be impossible to illustrate here 
the exact plan best to follow iji each individual case, and those 
undertaking the installation of a plant must be governed to a great 
extent by their requirements as they see them. 

It should be kept in mind when deciding what part of the 
factory can best be devoted to the tinning department that more 
or less gases and fumes prevail while the work is carried on. These 
gases and fumes are not only disagreeable to inhale, but are de- 
structive to fine machinery, tools and finished work. That the 
work may not become a source of annoj'ance to those who are not 
immediately engaged in it or destructive to machinery and stock, 
the tinning plant should be located if possible in a building by 
itself, taking care to provide good ventilation and drainage. 

A room devoted to this work should not be less than 10 feet in 
height, and it is a good plan to provide the kettles and acid tanks 
with hoods connected with ventilators to carry off the fumes. The 
hoods should, of course, be high enough to prevent interference 
with the work of the operators. 

The illustrations show tanks of cypress or pine for containing the 
different solutions used in preparing and finishing the work, but 
oil barrels sawed in half may be employed for the purpose if they 
are properly cleaned inside, either by burning or washing in a hot, 
strong solution of soda ash and water. 

For heating the tin hard coal is best, as it gives the most uniform 
heat and is most easily controlled. Soft coal, coke, natural gas 
and even wood can, however, be employed for the purpose. 



108 GALVANIZING AND TINNING 

Plan of a Tinning Plant 

We show in Fig. 42 a ground plan of a tinning plant intended 
for general work, except the tinning of common cast iron. In this 
illustration A is the roughing kettle — that is, the kettle used to 
give the work its first coating of tin; B is the finishing kettle; 
C is the tank containing muriate of zinc; D is what is termed in 




Fig. 42 — Arrangement of Equipment in a Tinning Plant 



the trade the "wjiipping box/' and is simply an arrangement to 
prevent the drops of molten tin being thrown promiscuously 
around the room when the operator is shaking or swinging his 
work to free it from surplus metal; E is a tank made of sheet 
iron for containing the kerosene oil used to cool the work in, the 
intent being to have this tank surrounded by cold running water 
to keep the oil cool, the water l)eing contained in the companion 
tank F ; G is a tank provided with a steam coil, the intent being to 
keep the tank filled with clean, hot water, in which to rinse the 
finished work before drying it off in the sawdust, which is con- 
tained in the box H; I and are water tanks used for storing 
the work after it has been cleaned in the acid; K is a tank con- 
taining muriatic or sulphuric acid; L and ]\I are acid tanks, the 
use of which will be explained in the proper place; N is a tank 
for containing a hot alkali solution, and it should be provided with 



TINNINC MALLEABLE IRON CASTINGS, WROUGHT IRON 



109 



a steam coil; E denotes a drain through the center of the room 
for carrying off the waste water. A sectional plan of this floor is 
given in Fig. 43. 



H 



/ 




/ 


y 


/ 




W^ 





Fig. 43 — Details of Floor Construction, Showing Drain 



Tools and Kettles 

The tools employed in handling the work are very simple in con- 
struction. They consist of wires formed into various shapes, ladles 
or baskets made from perfoi'ated sheet iron or wire cloth, and tongs 
with jaws formed to hold the various articles to be handled with 
them. Those illustrated l\y Fig. 25 in chapter on galvanizing will 
be found useful and all that will be required in many cases. The 
ingenuity of the operator will readily suggest what tools are re- 
quired for the work in hand. 

The number of tinning kettles necessary depends altogether on 
the class of goods to be tinned. The most common kinds of hard- 
ware specialties can be tinned very satisfactorily in a single kettle, 
while the better class of tinning, such as saddlery hardware, iron 
spoons, etc., require two kettles for best results, and even three 
may sometimes be employed to good advantage. 

Where a plant is fitted up for a fine grade of tinning, the kettle 
used to give the castings their first coating is called a "roughing" 
kettle, and the other kettle or kettles the "finishing." When a 
roughing kettle is used no particular care is taken to have the 
articles come from it smoothly coated or free from surplus tin, as 



110 GALVANIZING AND TINNING 

the unevenness of the coating will be removed by their treatment 
in finishing. The object of the roughing kettle is to give the iron 
a thorough coating of tin, as rapidly as it is prepared for receiv- 
ing it, to prevent rusting. After the iron receives a thorough 
roughing coat it may be stored away until required for finishing. 

For those having only a small amount of tinning to do it would 
not pay to invest in an expensive outfit of wet rolling barrels, and 
very good results can be olitained without them. In fact, only a 
few of the larger concerns engaged in tinning are so fitted, and 
their work is of a nature that requires the best results possible to 
obtain in the way of smoothness and brightness of finish. 



CHAPTER XIV 

Preparing the Work for Tinning 

ORDINAIiILY the common grades of tinned articles are 
made ready for tinning by simply removing the sand, 
scale or rust by pickling in commercial sulphuric, muri- 
atic or hydrofluoric acid, but the finer grades of work are pre- 
pared for tinning by careful and lengthy treatment in the water 
rolling barrel. 

Removing Scale and Rust with Sulphuric Acid 

Before steel and wrought iron will take a coating of tin all 
scale and rust must be removed. This is best accomplished with 
a pickle composed of 1 part sulphuric acid to about 30 to 40 of 
water, bringing the solution to a temperature of about 150 de- 
grees F. 

If the articles are of such shape that they will pack closely to- 
gether they must be stirred at intervals while pickling so the acid 
will have free action on all parts alike, otherwise the scale or rust 
will not be removed on the parts that come in contact with each 
other, the result being that the acid will burn the material ex- 
posed to the action of the pickle before the scale could possibly 
be removed from the parts in contact. 

In pickling sheets they must be placed in racks that will prevent 
one sheet lying against another. Sheets should be carefully in- 
spected, and any spots that the acid has not touched must be re- 
moved with the aid of a sharp-pointed steel tool. The shank of 
an old file ground to a point and hardened answers the purpose 
very well. 

If the articles are small, and it is desired to give them a fine 
surface, roll them in gravel and water after removing the scale 
and rust with the acid solution, and to further improve their sur- 
face give them a second rolling in scraps of leather. The effect 
of rolling is to give the articles a smooth surface, and the smoother 
the surface obtained iu preparing, the smoother and brighter will 
be the goods after tinning. 

We do not wish it to be understood that the rolling operation is 

111 



112 GALVANIZING AND TINNING 

absolutely necessary to obtain a complete coating of the goods, as 
they will take the tin perfectly if that operation is omitted, pro- 
vided they are properly cleaned, but their appearance is greatly 
improved by rolling, and when it is desired to obtain the best 
finish possible the rolling barrel must be employed. 

When the removal of scale and rust has been accomplished and 
the material is perfectly clean it should be stored in tanks contain- 
ing clear water, there to remain until the operator is ready to put 
it through the subsequent operations. Do not allow the work to 
remain in running water, as it will soon rust or oxidize. 

The operator must not fail to examine the work frequently while 
it remains in the hot pickle to determine when the desired result 
has been obtained. If it is allowed to remain too long a time 
after the scale and rust have been removed the acid will attack the 
surface of the material and leave it rougb and seamed. Imper- 
fections caused by overpickling cannot be eliminated by the coating 
of tin, and the commercial appearance of the goods will be injured. 

Cleaning Sandy Castings with Sulphuric Acid 

Castings that have sand on tliem must be subjected to a treat- 
ment that will effectually remove it, as a perfect coating cannot 
be obtained if sand remains. The removal of sand can be ac- 
complished by placing the castings on an inclined platform and 
keeping tbem wet with a cold pickle composed of 1 part sulphuric 
acid to 6 of water, until the sand is loosened enough to be washed 
off by a stream of water. From 10 to 20 hours is required to 
accomplish its removal, and then a casting brush must often be 
employed to remove all the small particles that are burned in where 
there are sharp angles. 

Kollnig- with plenty of sharp scratches or stars is the only sure 
way to obtain a perfectly smooth, clean casting, and we should 
never attempt to tin malleable castings in any considerable quan- 
tity without the aid of a rolling barrel. As in the case of steel or 
wrought iron articles, the wet rolling barrel supplemented by the 
dry rolling in leather scraps fits the castings to take a beautiful 
coating of tin with a bright luster. 

The platform on which castings are placed for pickling with 
sulphuric acid should have a tank placed under one end at its 
lowest point to catch the acid as it flows from the castings after 
each bailing operation. 



PREPARING THE WORK FOR TINNING 113 

Cleaning with Muriatic Acid 

The removal of scale and rust from wrought iron and steel can 
be accomplislied by a pickle composed of 1 part muriatic acid to 
15 to 20 parts of water, but the cost is greater and the result 
obtained no better. It is not advisable to use this acid for the 
purpose unless the amount of work to be treated is very limited 
and the sulphuric acid pickle is not available. 

In Fig. 42 K represents a tank to be used for the sulphuric or 
muriatic pickle, and I indicates the storage tank for the prepared 
work. 

Cleaning Sandy Castings with Hydrofluoric Acid 

We have given the course to be followed for cleaning sandy 
castings with sulphuric acid, because it may not always be pos- 
sible to obtain hydrofluoric acid. Where it is possible to substi- 
tute this powerful acid for sulphuric it should be employed, as its 
action is much more rapid and certain, and less destructive to the 
castings. 

In employing hydrofluoric acid to remove sand make a solution 
for slow pickling in the proportion of 1 part acid to 30 of water. 
For quick pickling make the proportion 1 of acid to 20 of water. 
Immerse the castings until the sand is dissolved, M^hich will be in 
from 15 minutes to 3 hours, depending on the strength and tem- 
perature of the solution and the tenaciousness of the sand. 

A good arrangement for doing this work is made by two or more 
small tanks for containing the castings elevated by a bench or 
stand a few inches above a larger tank containing the pickling 
solution. The castings are covered by solution bailed from the 
lower tank, which is easily drawn off after the castings are pickled 
by removing plugs fitted to holes in the bottoms of the smaller 
tanks. In this way the pickling solution can be used over and 
over again, while the castings can be easily removed for subse- 
quent treatments. 

Water Rolling 

This method of preparation not only effectually removes all im- 
pediments to a perfect coating, but gives the articles a perfectly 
smooth surface on which to deposit the tin, the degree of per- 
fection obtained being determined by the time and care expended 
in the rolling operation. Further information on the rolling and 



114 GALVANIZING AND TINNING 

tumbling of cast, wrought and malleable iron to be tinned is 
given in Chapter VI, pages 51 to 65. 

Removing Paint or Grease 

If the work has grease or paint on it, it must be removed and 
the sand blast will be found of great value for this work, although 
a hot solution of caustic soda or soda ash will often times accom- 
plish the desired result. Make the ' solution very hot and strong, 
and immerse the work in it until free from all such matter, after 
which rinse it thoroughly in clean water. This operation should 
precede pickling when necessary to perform it. The tanks for 
this purpose are designated in Fig. 42 as N and 0; N being the 
caustic soda tank and the rinsing tank. 



CHAPTER XV 

Applying the Coating of Tin 

AS ALREADY stated, very good results can be obtained by 
simply using one kettle of tin when the commercial ap- 
pearance of the work is of secondary importance. AVhere 
only a single kettle is employed the tin should be maintained at a 
temperature of about 500 degrees F., and the work may be cooled 
in hot water and dried off in sawdust. 

The operations preliminary to dipping the work in the tinning 
bath are precisely what they would be if more than one kettle was 
used. As these operations will be explained in connection with 
those for using two kettles, we will not give them here. 




Fig. 44 — Front Elevation 



Fig. 45 — Side Elevation 



Details of Tinning Kettle 

Where only a single kettle is employed more or less trouble will 
be experienced in keeping the dross or slag which rises to tlie sur- 
face of the tin from adhering to the work, and in keeping the tin 
at a uniform temperature. The dross or slag must be removed 
from the tin frequently with a perforated skimmer, and when the 
black flux that forms on the surface of the tin from the muriate 
of zinc, in which the castings are dipped previous to immersing 

115 



116 



GALVANIZING AND TINNING 



them in the molten tin, becomes present in sufficient quantities 
to interfere with drawing the worlv, it must also be removed in 
part. A small amount aids in the work, but when it accumulates 

in a sufficient quantity to 
catch on the work as it is 
drawn out it is apt to stain 
the work and leave white 
streaks wherever it touches. 
The cooling water should 
also be kept clean and free 
from acid. If it is not, the 
work is liable to be discol- 
ored and rust. In Figs. 44, 
45 and 46 we show manner 
of bricking in a single kettle, the casting details being shown in 
Fig. 47. 




Fig. 46 — Plan at Grate Line 



i 




I L I 



B=i. 




"^ a. 



Fig. 47 — Castings Required for Tinning Kettle 

Tinning with Two or More Kettles of Tin 

When the work has been made perfectly clean and free from 
sand, scale, rust, grease or paint by some one of the treatments 
described, it is ready for the final operations. If the work is of 
a kind that will admit of its being strung on wires, use such wires 
as seem best adapted to the work in hand. For many kinds of 
work a piece of wire bent in the shape of a croquet wicket, but 
larger, will be just the thing. Good stiff wires should be used, and 
they should be long enough to allow plenty of room for the operator 



Applying the coating of tin ii? 

to grasp the ends withoiit being burned. That is to say, if you 
have 10 inches of tin in the kettle, make the end of the wire 20 
inches long, which will allow 10 inches of wire out of the tin 
where the operator can grasp it when he is ready to draw the work 
from the kettle. Provide plenty of these wires so that the hand- 
ling of the work may be facilitated. 

String on wires as much of the work as you think you can 
handle comfortably, and put them, several strings at a time, into 
the alkali solution. The work may be allowed to remain in this 
solution for several minutes, or while the operator is filling more 
wires. From the alkali solution the work is to be passed into the 
rinsing tank, where care should be taken that all traces of the 
alkali are removed. 

When this is accomplished the work is to be given a few minutes' 
immersion in a solution of muriatic acid and water. This mix- 
ture should be in the proportion of 1 of acid to 4 or 5 of water in 
cold weather, while in warm weather 8 or 10 of water to 1 of acid 
will do the required work. The object of this dip is to remove 
any trace of rust that may have formed on the work. The tank 
for this purpose is designated as K in Fig. 42, and for many kinds 
of work, such as castings that have been cleaned by dry rolling, and 
goods made of material that has no scale, all that is necessary is 
to give it a few minutes' immersion in this solution. 

After this last dip of muriatic acid and water, which by the way 
should never be omitted, the work is to be dipped in muriate of 
zinc, which is the last dip previous to immersing it in the molten 
tin. Tank C, Fig. 42, is used to contain the muriate of zinc, 
which solution is made by dissolving scraps of zinc in clear muri- 
atic acid. 

Passing the Work Through the Tinning Kettle 

If two kettles of tin are in use, as shown in Fig. 42 by A and 
B, take a wire full of work to be dipped and plunge it while wet 
with muriate of zinc into the tin in the roughing kettle, desig- 
nated in Fig. 42 as A. Put several strings of work into the kettle 
at once and allow them to remain until the work is as hot as the 
tin, which, in this kettle, should be maintained at a heat of about 
500 degrees F. 

After the work has remamed in the roughing kettle for the re- 
quired time take a wire full in the left hand, and with a skimmer 



118 GALVANIZING AND TINNING 

in the right hand clear a space on the surface of the tin larg6 
enough to permit the wire full of work being removed without any 
of the dross or flux adhering to it. Eemove the wire full of work 
and pass it directly to the second kettle. It is not necessary to 
shake of? the surplus tin when removing work from the first ket- 
tle, but it is necessary to use care that none of the flux or slag is 
carried over to the second kettle on the work. 

While retaining hold of the wire the operator allows the work 
to remain in the second kettle for a fraction of a minute until the 
heat of the work attained in the first kettle is reduced to about the 
temperature of tlie tin in the second kettle, which for most purposes 
should be about 400 degrees F. Very small articles may require 
that the tin in the second kettle attain a temperature of 450 de- 
grees P. A little higher heat will cause the tallow, which is on 
the surface of the second kettle, to a depth of ^ to 1 inch, to 
ignite. When the Avork has about reached the heat of the metal 
draw it quickly from the tin, and after a few ra|)id swinging mo- 
tions to free it of surplus metal plunge it into the tank of kerosene 
oil, using motions calculated to keep the articles from sticking to- 
gether. A little practice will soon determine what motion is best 
for keeping the articles separated and preventing lumps of tin 
from forming on the work. 

D in Fig. 42 denotes the position of the box provided to catch 
the drops of surplus tin that are thrown from the work as the 
operator swings it to and fro. E denotes the tank for containing 
kerosene used for cooling, as already explained, and this tank 
should be surrounded by running water to prevent the oil "heating 
to a point where it would ignite. 

The work should be allowed to remain in the oil long enough to 
set the coating of tin, and should then be dipped in hot water and 
thrown into fine dry sawdust to dry it and remove the oil. If the 
articles are very heavy it may be necessary to plunge them into 
cold water after the oil. 

If small work cannot be strung on wires a "basket" may be used 
for dipping it. The basket may be made of sheet iron, in which 
case it should be well perforated to allow the tin to escape, or it 
may be made of wire cloth of a mesh sufficiently small to prevent 
the work falling through. Fig. 25 illustrates the shape of these 
baskets, which are designated as A and B. Nails, tacks, rivets and' 
all similar small articles are tinned by means of these baskets. 



APPLYING THE COATING OF TIN 11& 

Tongs are used for handling heavy articles, but those used in the 
tin should not be used for cooling the work, as they would mark 
it. The tongs used for cooling should not be put into the molten 
tin. The shape of tongs should be made to suit the form of the 
article to be handled. 

Tinning Wire in Coils 

In large' manufacturing establishments machinery is employed 
with which several strands of wire are passed through the tinning 
kettle simultaneously. To do the work on a small scale, provide 
reels that will accommodate a coil of wire. Place one of the reels 
in a position where the black wire will pass, as it is uncoiled, 
through a tank containing muriate of zinc through the kettle of tin. 
The other reel should be placed in a position where it will coil up 
the wire as it is drawn out of the tin. The reel used to draw the 
wire through the kettle must, of course, be provided with an ar- 
rangement for revolving it, and a device to hold the wire under the 
muriate of zinc and also under the tin as it passes through must 
be employed. As the necessary arrangement will readily suggest 
itself we do not think it necessary to illustrate it. 

At the point where the wire leaves the molten tin a piece of 
tow is twisted around the strand, sufficiently tight to wipe off the 
surplus metal, which flows back into the kettle. If the wire is 
very heavy it must pass through water after it leaves the tin, the 
water tank being placed where the wire will not enter it until it 
has passed through the bunch of tow used for wining off the sur- 
plus metal. 

If the wire is covered with a heavy scale or rust it must be 
cleaned in sulphuric acid the same as any other wrought iron or 
steel. If it is bright wire all that is necessary is to immerse it 
in a solution of muriatic acid and water, 1 part acid to 6 of water. 
If wire is to be tinned in large quantities a long, shallow kettle is 
best adapted to the purpose. 

Tinning Steel Spoons and Similar Articles 

For tliis purpose provide a good sized kettle for "roughing" the 
work — that is, for giving the first coating. For finishing the 
work use small kettles. A kettle 15 inches long, 8 inches wide and 
G inches deep is amply large for finishing work of this kind. We 
refer to a plant fitted especially for this business. The work can 



120 GALVANIZING AND TINNING 

be done in an outfit such as we illustrate by Fig. 42, but large 
finishing kettles are not as well adapted to this business as small 
ones, as the tin in a large kettle is apt to become dull in color by 
constant use, while in a small kettle the tin is renewed more often, 
which allows it to hold its color much better. 

In preparing the articles they should be rolled in tumbling bar- 
rels with scraps of leather and then carefully cleaned in an alkali 
solution. After rinsing off the alkali they should be immersed in 
quite a strong solution of muriatic acid and water for five or ten 
minutes, and then dipj)ed in the roughing kettle by means of a 
Avire basket, first dipping the work in a solution of muriate of 
zinc. As soon as they are thoroughly coated shake them out of 
the basket in such a way as to insure the separation of as many 
as possible. It makes no difference whether they come smooth or 
not so long as they are tlioroughly coated. The smoothness will 
come in the finishing operation. 

To finish the goods take one piece at a time in a pair of tongs 
adapted to holding them and immerse them in the finishing kettle, 
the tin in which is covered with beef tallow to the depth of about 
J inch. As soon as the article reaches the same heat as the tin 
remove it and allow it to cool until the tin will not run, after 
which wipe off the goods in flour. 



CHAPTER XVI 
Re-Tinning 

THE term re-tinning refers to the re-coating of pressed or 
stamped ware with tin. In the process of manufacturing 
tinware from tin plate by stamping or pressing, the origi- 
nal coating on the sheets is partly destroyed; hence, it becomes 
necessary to "re-tin" them; i.e., give them another coat of tin. 
It requires no little amount of skill to operate a re-tinning plant 
successfully, and satisfactory results are only obtained after long 
practice. For this reason, we omitted any extended mention of 
the art of re-tinning in the first issue of "Galvanizing and Tin- 
ning." Since the book was published, however, we have had so 
many communications from parties seeking information on the 
subject that we have decided to try and explain the process to the 
best of our ability. While perhaps our explanation will not enable 
the unskilled to successfully operate a re-tinning plant, it is hoped 
that what we have to say on the subject will not only prove of 
assistance to the novice, but to those already engaged in the 
business. 

Plant and Equipment 

The illustrations show the construction of a re-tinning stack 
Avithout going into dimensions, as the dimensions of the various 
kettles can only be determined by the class of work that it is 
desired to handle. We might say, however, that our illustrations 
of the kettles and brickwork of a re-tinning stack were made from 
a plant in operation on re-tinning ordinary kitchen ware, such as 
pressed dish pans, wash basins, etc., etc.; the actual dimensions 
of the kettles designated as A and C in Fig. 48 being 30" square. 
The dimensions of the kettle shown in the same Figure as B are 
24:" wide, 30" long and 2V deep, while the small kettle desig- 
nated as D, known as the "listing" kettle, is 6" wide, 12" long 
and from 3" to 4" deep. 

As indicated by Figs. 48 and 49 the outfit for a re-tinning plant 
consists of four kettles, A is what is known as the "soaking" 
kettle, and is used to contain molten beef tallow. B contains the 

121 



laa GALVANIZING AND TINNING 

molten tin and is known as the "tinning" kettle. C contains beef 
tallow and is known as the '-finishing" kettle, while D contains 
molten tin and is known as the "listing" kettle. 

The soaking kettle A contains beef tallow. In this kettle are 
immersed in rotation articles to be re-tinned. When the goods 
are received in the re-tinning room from the stamping room for 




vv7/y//X/////yy 



^m 




re-tinning, they are covered with various substances that have 
been used in the stamping room to facilitate the stamping opera- 
tion. This foreign substance usually consists of a solution of 
grease and soap, which must \)Q. removed before the articles are 
in proper condition for re-tinning. The soaking kettle is required 
not only for the removal of all foreign substance that has accum- 
ulated on the articles in the process of stamping, but to bring 
them to the proper heat for immersing in the tinning kettle B. 
In order to have the work proceed uniformly and systematically 
the soaking kettle A is provided with a rack or container, the 
general construction of which we illustrate by Fig. 50. The in- 
tent of these racks or containers is to prevent the articles from 
"nesting" together in the soaking kettle, thus retarding or entirely 



RE-TINNING 



123 



defeating the object for whieh this kettle is used. Ilcnce, it is 
obvious that these racks or containers must be made with a view 
to the proper accommodation of the articles to be handled. For 
instance, what is known to the trade as a six-quart pan would 
require a rack or container of a different size than would be 
used for a pan or article twice its size. The rack or container 




Fig. 49 — Plan of Re-tinning Furnace 



has another use; viz., that of preventing articles touching the 
sides of the kettle itself or sinking to the bottom and coming in 
contact with the refuse matter that has been removed from them 
in the process of "soaking." In this connection we will explain 
that whatever foreign substance is removed from articles sub- 
jected to the "soaking" process settles to the bottom of the kettle 
and in time becomes so hard that it is necessary to use consid- 
erable force to remove it. It often requires the use of a sharp bar 
to detach it from the kettle. The removal of this sediment is 
something that must be done at intervals of probably two or three 
weeks, although it may be found necessary on rare occasions to 
effect its removal at more frequent intervals. 

There are certain classes of stamped ware that do not require 
being held apart in the soaking kettle by a device such as we 
illustrate by Fig. 50, for the reason that their construction effec- 
tually prevents them from "nesting" together tightly or in such 



124 



GALVANIZING AND TINNING 




a way that the hot tallow in the soaking kettle could not readily 
effect the removal of whatever foreign matter has accumulated in 
the "stamping" or "spinning" process. The operator will readily 
understand that dishes with handles could not, owing to their 

construction, "nest" closely 
together. In such cases it 
is only necessary to use a 
rack or container that will 
effectually prevent the ar- 
ticles from settling to the 
bottom of the kettle or com- 
ing in contact with its sides. 
If the articles being treated 
do come in contact Vfith the 
sides of the kettle they are 
apt to be burned, which 
might effectually prevent 
their taking the tin, or they 

■ci cr> T> ^ o T^7 might become badly fouled 

Fig. 50 — Rack for Tinning Small Work *=> -^ 

with the sediment by touch- 
ing the bottom of the kettle. Where division racks in the con- 
tainer are not necessary, a wire basket of suitable size can be used. 
It is, of course, necessary to construct this wire basket or container 
in a way to obviate danger from the conditions just described. 

We have described the intent and use of the soaking kettle at 
considerable length for the reason that on its proper use, or, per- 
haps we should say, upon the proper preparation of the articles 
in the soaking kettle, depends almost entirely the success of sub- 
sequent operations. As the soaking process proceeds the supply 
of tallow in the kettle decreases; hence, it is necessary to add 
fresh tallow from time to time as the work goes on, or as fast 
as it is lost by evaporation, or burned, it often being ignited from 
over-heating. It also often happens that the tallow will ignite 
when the racks are removed at the end of the day's work, and, 
owing to this constant danger of fire, the several kettles must 
be provided with tight covers, which constitute the most practicable 
way by which the flames can be smothered. 

Where articles are being treated that require the use of racks 
or containers, a sufficient number should be used to insure constant 
and rapid operation. As from four to five minutes' immersion in 



RE-TINNING 125 

the soaking kettle is required on work stamped from heavy sheets, 
a suthcient quantity of containing racks should be provided to 
insure uninterrupted operation ; viz., enough so that the operator 
will always have a pan in the soaking kettle in proper condition 
for immersion in the tinning kettle. It, of course, necessarily fol- 
lows that after the container is once filled the operator replaces 
articles as fast as removed with others. 

The kettle designated us B is for containing the molten tin in 
which the work is immersed after it has been prepared in the 
soaking kettle A, The method commonly used is to have the man 
operating the soaking kettle pass the articles as fast as they are 
prepared over to the operator at the tinning kettle; using for the 
purpose a pair of tongs of proper construction, or, perhaps we 
should say, of proper shape, meaning of a shape fitted to the 
article and one that will not have a tendency to bruise or break 
it. When the operator on the soaking kettle has removed an 
article from his kettle he immediately immerses it in the tin con- 
tained in the kettle B, drawing it up and leaving it on the sur- 
face of the tin to be handled by the tinner, who grasps it with 
suitable tongs and again immerses it in the tin, manipulating it 
rapidly and in such a way as to prevent, so far as possible, any 
dross or, as it is termed by tinners, "scruff" from attaching itself 
to the article being handled. At this point the skill and experi- 
ence of the operator is exercised in keeping the tallow, which has 
been carried over from the soaking kettle, from attaching itself 
to the article being handled. AVe cannot very well describe the 
motions necessary to accomplish this object, as they can only be 
learned by experience. We wish to make it plain, however, that 
under no conditions must any of the grease from kettle A or B be 
allowed to be carried over into kettle C, as, in such a case, the 
contents of kettle C would be so badly contaminated that it would 
be impossible to produce good and satisfactory work. After the 
tinner who operates kettle B has accomplished the act of prop- 
erly removing the article in hand from the tin kettle B he places 
it in kettle C, which has been provided with racks for the holding 
of such articles as racks are necessary for in kettle A. Even 
the proper transferring of articles from kettle B to kettle C 
requires no little amount of ingenuity and experience. The im- 
mersion of articles from kettle B into kettle C must be accom- 
plished v/ithout rippling or disturbing the finishing tallow in ket- 



126 GALVANIZING AND TINNING 

tie C more than necessary, and the removal of articles from the 
finishing grease in kettle C must be accomplished in the same 
careful manner ; viz., so as not to disturb or agitate the hot grease. 

While it is essential that the tallow in the finishing kettle be 
kept clean and maintained at a uniformly proper heat, the best 
results are obtained after the tallow has been used for a time. In 
fact, satisfactory results cannot be obtained if the grease in this 
kettle contains too great a percentage of new tallow, or, as the 
operator would say, is too "sharp/' meaning that if the tallow is 
too fresh and new the finished work will either be streaked or 
have the coating removed in places. As the o1)ject of this ket- 
tle is to remove all surplus tin possible, it will readily be seen 
that it is necessary to bail out the tin which accumulates in the 
bottom of the kettle at frequent intervals. In large plants this 
is usually done at the end of the day's work, at which time all 
the tallow in the kettles A and C is removed, principally to obviate 
the danger of its igniting through the night, at which time the 
fires are usually in charge of the watchman. 

As each article is removed from kettle C the operator holds it 
in a position that will permit of what little surplus tin is left 
running to a given point, so as to permit its removal. This is 
accomplished by using a short rod of iron that is kept constantly 
immersed in the listing kettle. As soon as the drop has formed, 
and before it has time to harden, the operator takes the rod from 
the listing kettle in his left hand and draws it quickly and evenly 
over the place where the drop of tin has formed, much in the same 
way that a tinsmith would remove solder with his soldering cop- 
per. This explains the use of the listing kettle D. It is simply 
used for containing sufficient tin in a molten state for immersing 
the end of the listing rod, so that it will always be handy and in 
proper condition for removing the drops of tin as they form on 
the finished work. 

The proper degrees of heat for the contents of the different 
kettles can only be determined by experience and practice. The 
tallow in the soaking kettle A must be maintained at very close 
to the heat of the molten tin in the tinning kettle B, and it is 
obvious that the tallow in the finishing kettle C must also be 
maintained at approximately the same temperature. 

No more than two articles should be immersed in the finishing 
kettle at one time. If there are, one is almost sure to be spoiled. 



RE-TINNING 127 

As wo have explained, this finishing kettle C is used for remov- 
ing tiie surplus tin, and for this reason is called by tinners the 
"skinning" kettle. 

In handling very large work the racks or containers are left 
out of the soaking kettle, and in their place a sheet of tin is 
dropped into the bottom of the kettle so as to keep the articles off 
the bottom. This sheet should be taken out at night. 

As fast as the work receives the finishing touches from the man 
operating the finishing kettle, it is placed on racks and allowed to 
remain there until it is cool enough to be handled by the operators 
who give it the final finish. The finishing force for a re-tinning 
stack usually consists of three girls. For their use a long bench, 
E, Fig. 4:9, is provided. The first operator gives the work a 
thorough rubbing in dry soft sawdust contained in box F. The 
second goes through the same operation with SAvadust, mixed with 
what is known as "middlings" or wheat bran, and contained in 
.box G, while the third performs the same operation with a cheap 
grade of flour, contained in box H. From there it is finished 
at the wiping bench J. 

We will say, in a general way, that it is not necessary to im- 
merse articles that are to be re-tinned in acid unless, by chance, 
they have become rusty through carelessness in some operation or 
by letting them stand too long after leaving the stamping ma- 
chines. When it is necessary to remove rust by the use of acid, 
the articles must afterward be thoroughly rinsed in clean water, 
after which they should be dipped into boiling hot water and 
carefully and thoroughly dried liy the use of saAvdust. 

In providing tongs for handling the work through the various 
kettles, only those made of steel should be used, and they should 
be carefully cleaned and coated with tin before being used. Care 
should be taken to select tongs suited to the variety of shapes 
being handled. 

As dross forms in the tinning kettle very rapidly, it is neces- 
sary to take measures to prevent its interfering with the work. 
This is done by an operacion known as "boiling" the tin, and is 
accomplished by forcing a large block of green wood, preferably 
white pine, to the bottom of the tinning kettle and causing it to 
remain there the desired time by some simple device adapted to 
the purpose, usually by means of a rod of iron inserted in a hole 
bored in the l)lock. These blocks of green wood should be previ- 



128 GALVANIZING AND TINNING 

ously dipped in hot tallow ; otherwise, they would cause the molten 
tin to spatter in all directions when the blocks were immersed. 

In order to facilitate the removal of the kettles from the brick 
work when it is necessary to replace them for any purpose, and 
also to assist in the removal of the containers in the several kettles 
when it is desirable to remove them, a strong bar of iron should 
be built into the stack high enough to permit the use of a chain 
hoist. A few bars or rods of iron should also be built into the 
stack above the kettles, on which sheet iron can be laid to pre- 
vent the soot that gathers in the stack from falling into the ket- 
tles and thus spoiling the contents. 

Fig. 48 is a sectional elevation of a re-tinning stack, and, as 
shown by Fig. 49, the kettles are fired on the opposite side from 
where the workmen stand when operating the kettles. In order 
to have easy access to the fires and to facilitate the removal of 
ashes, a pit is provided which should be large enough to attain 
its object. The depth of the pit is governed entirely by the depth 
of the kettles. 

It will be observed by referring to Fig. 48 that the kettles are 
heated on the sides, as well as on the bottoms, which is accom- 
plished by means of spiral flues designated as K : these spiral flues 
having an outlet into the large flue L, shown in Fig. 49, and 
which is a separate flue from the one designed to carry off the 
fumes and smoke rising from the kettles. 



CHAPTER XVII 

Tinning Gray Iron Castings 

ONLY a few years ago all articles used in the preparation 
of food which were made of gray iron were zinc coated or 
galvanized, as they could not be tinned satisfactorily. This 
fact, and the fact that tin was a much more desirable metal than 
zinc for coating articles used for culinary purposes, was largely 
responsible for a method of tinning gray iron which was perfected 
by the author. To-day it is almost impossible to sell zinc-coated 
articles used in the preparation of food, as such articles made of 
gray iron are now tinned extensively. For example, ice cream 
freezers, lemon squeezers, meat cutters, bread and cake mixers, 
egg beaters, fruit stoners, vegetable cutters, etc., made wholly or 
in part of gray iron and tinned are now sold imiversally. 

In addition to the uses to which tinned gray iron is put by 
the manufacturers of kitchen and other hardware specialties, it 
has been found of great advantage to give articles of cast iron 
that are to be copper or brass plated a coating of tin previous to 
plating them. The advantages come from the lessened quantity of 
material necessary to use in electroplating, the preventing of 
"leaking" or "sweating," so common where the plating is deposited 
directly on the bare casting, and also from giving the articles the 
appearance of spelter or brass castings. 

By this process gray iron castings are prepared for tinning by 
rolling them in a solution of muriatic acid, sal ammoniac and 
water, the rolling barrel being constructed to retain, under pres- 
sure, the gas formed by the chemicals used. The use of this bar- 
rel makes it desirable to locate the tinning plant in a building by 
itself, as the gas generated is constantly escaping, carrying with it 
quantities of the solution. At the best the rolling room for gray 
iron tinning is a wet, dirty place, and the entire operation re- 
quires the use of considerable water. 

Plant and Equipment 

In erecting a building for this purpose particular attention should 
be paid to ventilation and drainage. A plan for constructing a 

129 



130 



GALVANIZING AND TINNING 



floor, with a view to perfect drainage, is shown by Fig. 43. Two 
or more kettles (depending on the nature of the work), set after 
the plan illustrated by Figs. 52, 53 and 54 and various tanks built 
after Fig. 24, complete the outfit. The arrangement of the outfit 




Fig. 51 — Arrangement of Tinning Plant 

•is shown by Fig. 51, in which A is the rolling barrel for preparing 
the castings for tinning. B is a tank to receive the castings after 
they have been treated in the rolling barrel A. This tank should 

be provided with trucks, and a track 
should be laid so that the tank can be 
run under the rolling barrel to receive 
the prepared work. C is a water tank 
for storing the prepared castings after 
rolling, as hereafter described; D, E, 
F and G are divisions of one common 
tank; D is to contain an alkali solu- 
tion, and should be provided with a 
steam coil, as shown, to heat the solu- 
tion; E is a compartment for contain- 
ing water for rinsing; F is to contain 
an acid solution; G is for the muriate 
IS tne rougning kettle of tin; K is the fiin- 
ishing kettle; L is the kerosene for cooling: the work. The 




Fig. 52 — Front Elevation 
of zinc; H is the roughing 



arrangement of this tank was explained in the chapter on 



TINNING GRAY IRON CASTINGS 



131 



general tinning; M is a wooden tank large enough to ac- 
commodate the iron tank L and allow it to 1)C surrounded 
with water: N is a tank for containing hot water, in which the 




Fig. 53 — Side Elevation of Tinning Furnace 

tinned work is dipped to remove any traces of oil or acid, and 
is provided with a steam coil, as showai; is a box to contain 
sawdust for drying oil the work when it comes from the hot water 




Fig. 54 — Plan of Tinning Furnace at Grate Line 



contained in the tank N ; E E is a drain for carrying off the waste 
water, and S S are the tracks for moving the tanks B and C; 
T is a tank for containing a solution of hydrofluoric acid, used 
as hereafter described, and U is a storage tank. It is perhaps 



132 GALVANIZING AND TINNING 

needless to say that tlie ground plan may be changed to suit local 
conditions. 

Only the most simple tools are required, which may be varied 
Ijv the ingenuity of the operator to suit existing conditions of 
work. We give a sketch showing the most common in Fig. 35. 



CHAPTER XVIII 

Preparing Gray Iron Castings for Tinning 

IN PREPARING gray iron castings to take a coating of tin 
there are several essential things to be taken into considera- 
tion ; viz., the quality of the iron, the form of the castings, 
their condition when they come to the tinner and, if cored, the 
nature of the cores used. 

Hard iron requires longer preparation than soft iron and a 
longer immersion in the molten tin. Castings made from patterns 
not designed with a view of avoiding sharp angles, and in which 
molding sand can easily find lodgment, are much more difficult 
to prepare than those made from patterns free from such 
hindrances. It is, of course, not always possible to do away with 
sharp angles in making patterns for castings that are designed to 
be tinned, but whenever possible they should be avoided in the 
interest of easy cleaning and perfect coating of the work. 

Castings that have been freed from sand by the use of sulphuric 
acid require a special preparation before they will take a perfect 
coating of tin, and the use of this acid for this purpose should 
be avoided if possible. Cored castings made with cores in which 
rosin has been used must be treated differently from those made 
with an oil or glue core. For the intelligent understanding of the 
different conditions we give the specific course to be followed in 
each case. 

The perfect coating of gray iron requires the use of two tin- 
ning kettles, and where castings are to be tinned previous to elec- 
troplating three kettles of tin should be used to insure the smooth- 
est coating and the brightest luster. 

Removing Sand from the Castings 

The first operation in preparing the castings for tinning is to 
free them from sand. This is best accomplished by the use of 
the ordinary tumbling barrel, which gives the castings a smooth, 
clean surface while removing the sand. "Where the castings are of 
a nature which prevents their perfect cleaning by tumbling, the 
sand should be removed by a solution of hydrofluoric acid and 

133 



134 GALVANIZING AND TINNING 

water. Sulplmric acid will do the Avork, but in a much inferior 
manner and to the detriment of the castings as regards their easy 
and perfect coating in the tin. The reason for this is easily under- 
stood. Hydrofluoric acid acts directly on the sand, dissolving it 
rapidly without attacking the iron to any great extent. The action 
of suljDhuric acid is just the reverse, the iron being dissolved on 
the surface of the casting, causing the sand to fall off, the sand 
itself not being affected. 

Freeing Gray Iron Castings from Sand by Hydrofluoric Acid 

While this operation is about the same as given for cleaning 
malleable iron by the use of this acid, we wish to impress the 
operator with the fact that in treating gray iron with acid of any 
kind, in preparing it for tinning, much more care must be exer- 
cised in the operation than with malleable iron, as the over- 
pickling of gray iron leaves the surface soft and gummy, in which 
condition it will not take a coating of tin and it is no easy 
matter to put it in a condition where it will. 

For quick cleaning of sandy castings by the use of hydrofluoric 
acid the preparation should be 1 of acid to 20 of water. For 
slow cleaning, which is necessary on castings having sharp angles 
into which the molding sand has burned, use the acid in the 
proportion of 1 of acid to 30 of water. The castings may remain 
in this solution until the sand is dissolved, after which, provided 
they have not been made with rosin cores, they are ready to be 
placed in the tuml)ling barrel used to prepare them for tinning. 
If rosin cores have been used the castings are to be treated in 
a special way, which will l)e explained in its turn. 

A good arrangement for cleaning sandy castings with hydro- 
fluoric acid is to have two tanks (oil barrels sawed in half will 
answer), one elevated alcove the other by means of a stand or 
bench, so that the top of the lower tank will be 3 or 4 inches below 
the bottom of the elevated tank. Bore a hole in the side of the 
upper tank close to the bottom and provide a plug. Place the 
castings in the upper tank and cover them with the hydrofluoric 
solution, which is contained in the tank below. When the cast- 
ings have been completely freed from sand remove the plug and 
allow the solution to escape into the tank below, where it remains 
until required for use again. No specific rules can be given as 
to the time required to clean castings, and it is not necessary, as 



PREPARING GRAY IRON CASTINGS FOR TINNING 135 

an examination of the work from time to time wliile under treat- 
ment will determine wlien they are clean. Castini^s on which a 
light deposit of sand is attached may be clean after 15 minutes' im- 
mersion in the solution, while castings having a heavy coating of 
sand, or on which the sand has burned, may require 3 or 4 hours. 
If the nature of the sand on the castings makes it seem prob- 
able that they will require a longer immersion in the acid, weaken 
the solution by the addition of water to a point where there can 
be no possible danger of the castings being affected in the way 
mentioned in the beginning of this subject. 

Cleaning Sandy Castings with Sulphuric Acid 

If sulphuric acid is used to free the castings from sand, place 
them on an inclined, raised, platform, which platform should be 
of a size to accommodate the intended production and arranged 
to allow the solution to flow back into a tank placed at the lowest 
point to receive it. Make the solution in the proportion of 1 of 
acid to 6 of water, and keep the castings wet with this solution 
until the sand can readily be removed by a stream of water. Gray 
iron castings cleaned in this way will have a soft, gummy surface, 
and will not take as perfect a coating of tin as castings cleaned by 
dry tumljling or by the use of hydrofluoric acid. They must be 
given a special treatment before tinning, which will be described 
in connection with the treatment of castings made with rosin 
cores and hard or greasy castings. 

Cleaning Castings with the Sand Blast 

In addition to the methods already described for preparing 
gray iron castings for tinning, the reader should not lose sight 
of the fact that the sand blast is a valuable agent for this pur- 
pose, and we strongly advise those who have sufficient work to 
warrant the installation of a sand blast plant to carefully inves- 
tigate its possibilities. ' Special attention is given to this subject 
in Chapter VI, pages 51 to 65. 

The Use of a Hot Alkali Bath in Certain Cases 

After the castings have been freed from sand in some one of 
the ways described, provided they have not been over-pickled, or 
made with rosin cores, or greasy, and have not been faced with 
black lead facing, or picked with sulphuric acid, they are ready 
for tumblino: in the solution of muriatic acid, sal ammoniac and 



136 GALVANIZING AND TINNING 

water. If any of these conditions should prevail, the castings 
must be given a treatment in a bath of hot caustic soda or soda 
ash. 

If castings have been over-pickled — that is, left in the pickle 
until the surface has become covered with a soft, gummy sub- 
stance — or if rosin cores have been used in making the castings 
or black lead facing used to give a smooth surface, or if grease 
or paint is present, they must be immersed for several minutes 
in a boiling solution of caustic soda or soda ash. Make the solu- 
tion very strong, and see that the strength is maintained by adding 
fresh material as needed. 

After this treatment the castings must be thoroughly washed 
with clean water before they are placed in the rolling Ijarrel used 
to prepare them for tinning. D in Fig. 30 designates the tank 
to be used for the hot alkali solution and E, in the same illus- 
tration, is the tank used for rinsing. 

Tumbling 

Special care is required in preparing cast iron for tinning, in the 
tumbling barrel and a very comprehensive treatment of the subject 
is given in Chapter VI, pages 51 to 65. This material covers the 
construction, location, charging and operation of the barrel. 

The important point to keep in mind in preparing cast iron for 
tinning is that the surface of the iron must be made perfectly 
clean. Not only free from sand and rust, but from every foreign 
substance. It may seem to the reader that we are dwelling on 
this point unnecessarily, but only by the most careful attention to 
the proper preparation of the castings, and in the keeping of them 
in the same clean condition until they receive the first coat of tin, 
can perfectly satisfactory Avork be obtained. 

If the iron is allowed to roll in the solution too long a time 
the surface Ijecomes soft from the action of the acid and tlie tin 
will not take. The same trouble will be experienced if the solu- 
tion in the rolling barrel is too strong, or if the castings are 
allowed to remain in the solution too long after they are rolled. 

Water Rolling 

Where castings are tinned for the purpose of electroplating 
them, it is desirable, if an extra smooth surface is desired, to 
give them a rolling in gravel and water in the ordinary wet 



PREPARING GRAY IRON CASTINGS FOR TINNING 137 

rolling barrel, although tliis treatment is not necessary in order to 
prepare tliem to take a coating of tin. In treating castings in 
this way use a coarse hard gravel, and some castings may be 
rolled 20 to 30 honrs to good advantage if the barrel is properly 
loaded. 



CHAPTER XIX 

Coating Gray Iron Castings with Tin 

THE tin ill the kettles being at the proper heat for the work 
in hand, as specified later on, the operator takes a small 
quantity of the castings from the storage tank C, Fig. 51, 
and places them in the wire basket designated A in Fig. 35, tak- 
ing care to place those having concave sides, holes or depres- 
sions so that none of the various solutions, through which they 
are now to pass, will be retained. The castings contained in the 
basket must now be immersed in the solution of caustic soda or 
potash, which is contained in tank D, Fig. 51. This solution 
must be kept at the boiling point, and from 1 to 2 minutes is 
svfficient time to leave the castings in. The best plan for heat- 
ing this solution is to have a steam coil in the bottom of the 
tank, as shown in the illustration, and to allow the exhaust steam 
to pass into the rinsing tank, which is placed beside it, as shown 
in the ground plan. The rinsing tank is designated E in Fig. 
51. After the basket of castings has stood in the alkali bath con- 
tained in tank D for the desired time it is placed in the rinsing 
tank E until all traces of that solution are removed. This will 
take but a fraction of a minute, provided a stream of clean water 
is kept flowing into the tank, as it should be , In rinsing the cast- 
ings in tank E do not allow them to remain in the tank for any 
great length of time if water is flowing in, as iron will soon rust 
in running water. 

The next move is to immerse the basket of castings in a very 
weak solution of muriatic acid and water, 1 part acid to 40 of 
water. The tank for containing this solution is designated F in 
Fig. 51, and the castings must not be allowed to remain in it 
more than 2 or 3 seconds. The solution should be made up fresh 
after 2 or 3 tons of iron have passed through it. 

Next, place the basket of castings in the tank G, Fig. 51, which 
contains muriate of zinc, to which has been added 5 pounds of 
gray granulated sal ammoniac for every gallon of the liquid. 
Muriate of zinc is made by dissolving zinc in muriatic acid, allow- 

138 



COATING GRAY IRON CASTINGS WITH TIN 139 

ing the acid to dissolve all the zinc it will. An earthen crock 
or a cleaned oil barrel can be u^■ed to make this cut acid in. This 
solution should be deep enough to cover the castings contained in 
the wire basket used for immersing them in the roughing kettle, 
and should be kept in good condition — that is, care should be 
taken to prevent its being weakened to any great extent by pass- 
ing the solution in tank F into it with the work. The tank for 
containmg this muriate of zinc should be lead lined, and an inner 
lining of wood used to protect the lead. 

The basket of castings is now ready to be immersed in the 
molten tin contained in the first, or roughing, kettle, and shown 
in Fig 51 at H The tin in this kettle should attain a heat of 
500 degrees F., and this heat should be maintained during the 
time the kettle is in use. 

Before immersing the castings in this kettle the surface of the 
tin should be covered by a flux, made by boiling a quantity of 
the muriate of zmc on top of the molten tin, and adding quickly 
to the boiling mass a quantity of white granulated sal ammoniac. 
The sal ammoniac must be added by sprinkling it on before the 
acid is evaporated by the heat of the tin It will take a little 
time and experience before the proper consistency of this flux can 
be attained The proper making of this flux is one of the most 
essential points in the successful coating of cast iron in this first 
kettle of tin. If the flux is allowed to become hard and dry, as 
it soon will by continued use unless careful and constant atten- 
tion is given to it, the flux will adhere to the castings as they pass 
through it into the tin below, and thereby prevent them from 
coating. 

When it is found that the flux is becoming thick and lumpy, 
add a sufficient quantity of muriate of zinc and powdered sal am- 
moniac to cause the flux to boil up to a depth of ^ inch or more. 
When this result is obtained take a perforated iron skimmer and 
carefully remove any hard lumps and congealed matter remain- 
ing in the flux, allowing such as readily pass through the skim- 
mer to remain in the kettle. The purpose of this flux is to pre- 
vent the surface of the tin from becoming oxidized by exposure 
to the air, and also to prevent the hot metal from spattering and 
burning the operator when the wet castings come in contact with 
the tm. Bear carefully in mind that this flux must at all times 
be kept in a thin liquid condition, otherwise the succeeding opera- 



140 GALVANIZING AND TINNING 

tions through which the castings are to pass before they are com- 
pleted will be unsuccessful. 

In forcing the castings into the roughing kettle, care should be 
taken to get them immersed as soon as possible. If they are 
allowed to float on the surface of the tin the muriate of zinc, 
with which they are wet (for the purpose of causmg the tin to 
adhere), will dry off, and the tm will not adhere to the part of 
the casting thus exposed The castmgs must be kept below the 
surface of the tin until they have become as hot as the tin itself, 
and until the tin has ceased to bubble or to be agitated by the 
castings that are immersed. This boiling or agitation will cease 
when the air and moisture is expelled from the iron and the flux, 
that adhered to it as it passed through, has risen to the surface 
of the tin. 

The proper way to immerse the work in this first kettle of tin 
is to rest the handle of the basket containing it on a block of 
iron placed on the edge of the tin kettle, elevating the basket at 
an angle that will prevent it touching the molten tin until the 
operator is ready to have it. Cant the basket so that one of the 
lower edges will enter the tin first; in other words, do not allow 
the flat bottom of the basket to come directly onto the surface of 
the tin, as the effect of having as much wet metal as the bottom 
of the basket presents coming in contact with the molten tin will 
be an explosion, resulting, perhaps, in the serious injury of the 
operator or some one standing near. When the basket is in the 
described position, lower it carefully until 1 inch or 2 inches of 
the bottom and one side is immersed in the tin, then lower rapidly, 
but steadily, until the basket and its contents are completely 
immersed. 

At this point turn the basket completely over, bottom up, and, 
using the edge of the tin kettle as a rest for the handle, lift the 
basket from the tin when it is free. Turn it bottom down and 
use it in that position to keep the castings it contained below the 
surface of the tin until they reach the heat of the metal. Fill 
the kettle with as many castings as it will hold and allow them 
to be completely immersed. Several of the wire baskets may be 
employed to insure having a batch always ready to immerse when 
a previous one has been disposed of. 

It sometimes happens that the operator carelessly omits dip- 
ping the work in the cut acid contained in tank G, Fig. 51; that 



COATING GRAY IRON CASTINGS WITH TIN 141 

is, he may attempt to immerse the work in the molten tin directly 
from tank D, E or F. Such neglect is dangerous and likely to be 
attended with serious results to the operator, due to spattering of 
the hot metal. 

There are many kinds of castings that may be strung on wires 
and handled through the different stages without the use of 
wire baskets. When wires are used the shape may be varied to 
suit conditions. While we show the most common in Fig. 25, the 
ingenuity of the operator mu3t ho employed in selecting and de- 
vising those best adapted to his wants. 

The kettle being filled, as described, the castings must now 
remain where they are for from 5 to 15 minutes, or until they 
have taken a perfect coating of tin. If, in this time, they are 
not properly coated, some error has been made in the previous 
operations and the work must l)e re-rolled. 

What dross or slag forms in a tin kettle rises to the surface. 
A considerable part of this objectionable matter will be found in 
the first kettle, and must be removed before the work can be car- 
ried to the finishing kettle or kettles. To accomplish the removal 
of this dross, or slag, floating on the surface of the tin, use a 
perforated, concaved iron skimmer. The holes in the skimmer 
should be large enough to allow the clear tin to flow through 
freely, and care should be taken not to waste the flux in skim- 
ming out the dross. If the skimmer is canted edgewise the dross 
will adhere to the skimmer, while the flux and clear tin will flow 
back into the kettle. 

When all the dross has been removed from the kettle, grasp 
one of the castings with a pair of tongs and remove it with a 
quick motion from the tin. If wires have been employed for 
stringing the work, take one or more wires and remove in the 
same way to the next kettle, taking care that no flux or dross is 
carried along with the work. The temperature of the tin in the 
first kettle is much too high for finishing work, and when the 
castings taken from it are exposed to the air they will turn more 
or less yellow, depending on the heat of the tin. A bright yellow 
or golden color indicates too high a heat and must be avoided. 
A slight yellowish tinge indicates the proper heat. 

The tin in the second kettle, which is designated in Fig. 51 as 
K, and which, in most cases, is the finishing kettle, must be main- 
tained at a temperature of about 400 degrees F., and the surface 



142 GALVANIZING AND TINNING 

must be kept covered to the depth of from ^ to 1 inch with pure 
beef tallow. Palm oil may be introduced into the tallow with good 
results, using about 10% palm oil. The operator keeps the cast- 
ings held by the tongs or wires immersed in this second kettle 1 
or 2 seconds and then, with the tongs held in the left hand, he 
removes the piece from the tin. As soon as the piece is clear of 
the tin the operator grasps it with another pair of tongs held 
in the right hand and, after a few rapid swinging motions to free 
the article from surplus tin, plunges it into the tank containing 
kerosene oil. If wires are being used he swings the work to 
and fro rapidly to free it from the surplus tin, and when plung- 
ing it into the oil he must give the work a motion calculated to 
prevent the articles in contact from adhering to each other. 

The tank, which is designated in Pig. 51 as L, should be of 
sheet iron and placed in the companion tank ]\I with the idea of 
having running water surrounding it to keep the kerosene from 
becoming over-heated, as it soon would be from having hot cast- 
ings continually immersed in it. The work must be immersed in 
this oil long enough to set the tin and then immersed in the 
cold water contained in the companion tank M. 

If the tin in the finishing kettle is at the right temperature 
the work will be white and have a nice luster after it is cooled. 
If the work is rough and lumpy it indicates that the tin in the 
finishing kettle was not hot enough or that the work was kept in 
the air too long a time before dipping it in tlie kerosene. The 
tin in the finishing kettle requires very little fire to be maintained, 
as there will be nearly enough heat in the castings brought from 
the first kettle to keep the tin in the second at a proper heat. If 
the work is yellow after cooling in the oil it may indicate too 
high a heat in the finishing kettle, or it may indicate that the 
casting was not kept in the finishing kettle long enough to bring 
the heat that the casting attained in the first kettle down to a 
point where the tin would not turn yellow. 

Work can be taken from the finishing kettle smoothly and 
brightly coated even Avhen the temperature of that kettle is so 
low that if a piece of cold iron be put into it the tin would adhere 
to the iron in a thick mass. The heat the castings attain in 
the first kettle makes it possible to run the finishing kettle at a 
very low temperature, and it is advisable to do so on very heavy 
castings. Light castings require that a much higher heat be 



(()Aiix(; (;ray iron castings with tin 143 

maintained in tlio iinishing kettle than is necessary for heavy 
castings. The reason is apparent: All castings must be exposed 
to the air a few seconds while the operator is switching off the 
surplus tin. If the castings are light and the tin is cold they 
will not hold the heat long enough to allow the surplus tin to be 
shaken off without leaving rough, ragged edges. 

A great deal of ingenuity can be displayed by the operator in 
the handling of castings of various shapes in such a way that 
no lumps or bunches of tin will remain on the work after it is 
cooled. For example, care should be used to ascertain what part 
of a casting is best adapted to Ije taken hold of by the cooling 
tongs without leaving marks of the tongs after the article is 
cooled. The tongs used for cooling should never be put into the 
tin kettle, as the heat of the casting would cause it to adhere 
to the tongs if they were tinned. After shaking off the surplus 
tin, change the position of the casting so that the drop of tin, 
which will naturally collect at the lowest point, will flow back 
into the coating on the casting, and dip it in the oil at once when 
this is accomplished. 

A "switching box" should be employed, when "strung" work is 
being handled, to catch the tin that is thrown from the work 
in the operation of "switching" it to throw off the surplus metal. 
This box is a very simple affair. Its position, when in use, is 
designated D, Fig. 33. Cover the interior of the box with heavy 
paper, as the hot tin will stick to the wood unless paper is used. 
The tin thus collected may be thrown into the kettle with the 
paper when the tin is needed for use. 

When the castings have l^een cooled, as already described, they 
should be immersed in a tank of boiling water to free them from 
oil and also to remove any trace of acid that may be on them. 
This final rinsing tank is designated N in Fig. 51. The water 
must be kept clean and at tlie boiling point at all times when 
in use. An ordinary foundry riddle, with upright handles long 
enough to allow the operator to set the riddle containing the work 
to be rinsed into the tank without scalding his hands, may be 
employed. 

The castings should be dried oft' in clean dry sawdust, and that 
made from pine or some soft wood is best, as hard wood sawdust 
will scratch the tinned surface. The drying box is shown at in 
Fie-. 51. 



144 GALVANIZING AND TINNING 

When three kettles of tin are employed, as they may be to good 
advantage in tinning work that is designed to be plated, the 
second kettle must be run at a temperature of 450 degrees F. The 
surface of the tin in this kettle must be kept covered with an 
acid and sal ammoniac flux the same as the first kettle. The 
castings in the first kettle are passed in quantities to the second 
kettle, there to remain until the first kettle is refilled. As when 
using two kettles, care must be taken to prevent any of the slag 
or flux that accumulates on the first kettle from passing with 
the work into the second kettle, and the tin in the second kettle 
must be kept free from slag. 

The tin in the third or finishing kettle should be maintained 
at a temperature of 400 degrees F., and the depth of the tallow 
increased to 3 or 4 inches. 

If three kettles are employed they should be square or 
round, and arranged to fire from one side instead of from the 
ends. 

As it is almost impossible to satisfactorily tin castings which 
have been imperfectly coated at the first attempt, the operator 
should give careful attention to details. 

It is comparatively easy, with practice, to keep the tin at a 
proper heat, but the beginner will find more difficulty in doing 
this than any other one thing in the entire operation. That the 
proper heat be maintained is very essential, for if it is not all 
previous care in preparing the work will have been in vain. If 
too hot the flux on the roughing kettle will evaporate or burn off, 
and the tin will not coat the iron. If too high a heat is reached 
on the finishing kettle the tallow will be set on fire. As a help 
to the novice and, in fact, to the experienced man, we recommend 
the use of pyrometers; one for each kettle. The expense of pro- 
viding them is not to be considered in comparison with the ad- 
vantages obtained by their use. 

The kettles for containing the tin usually are made of cast 
iron, although fire box steel is often emj)loyed to make oblong 
kettles. 

A fioor space of 20 x 40 feet will accommodate a tinning plant 
having two rolling barrels. If possible, the plant should be lo- 
cated handy to power and with a view to obtaining easy and per- 
fect drainage. If necessity compels locating the plant in a fac- 
tory building above the ground floor, as is sometimes the case, the 



COATING GRAY IRON CASTINGS WITH TIN 145 

floor of the. tinning and rolling rooms must be so constructed that 
leakag-e into the room or rooms below will be impossible. 

The dross or slag formed in the kettles should be stored away 
until a sufficient amount lias accumulated to make profitable the 
remolting of it to reclaim what pure tin is in it. For the pur- 
pose of remelting this dross the pure tin can be removed from 
the kettle II, Fig. 51, and the dross melted up in it. When the 
entire mass is in a molten state, and at a temperature of about 
550 degrees F., l^ail off the good tin into cast iron pans provided 
for the pui'posc, and the dross which remains into separate pans. 
This tin dross has a market value of from 40 to 50% of the 
price of pig tin. 

With the addition of tanks for containing cleaning acids, a plant 
built to tin cast iron is adapted to all descriptions of tinning, 
excej)t re-tinning of tinware and the tinning of sheets. 



CHAPTER XX 
Cleaning Old Galvanized and Tinned Work 

GALVANIZED material becomes dark or discolored from 
age or exposure and from various other causes. Gal- 
vanized sheet iron is often found to be covered with a 
white deposit, which discolors them even when the stock has been 
kept under cover, and it is almost sure to be found if it has 
been subjected to changes of temperature which have caused mois- 
ture to gather on the sheets. On galvanized castings the discolora- 
tion is seen in the form of a white powder which forms on their 
surface, or, if they have been stored in a room not subjected to 
marked variations of temperature, their surface simply turns 
dark. 

While it is practically impossible to prevent this discoloration, 
and while it is not particularly detrimental to the wearing qual- 
ities of the coating, it is often detrimental to the sale of the mate- 
rial, as few care to buy goods that have a "shop-worn" appearance. 
The appearance of discolored material may be materially improved, 
however, and sometimes made to look like new, by dipping it in 
a cold solution of one part sulphuric acid to ten parts water. The 
material should not be left in the acid dip more than two minutes 
at the most, and as much less as possible, and accomplish the 
desired result. Neither should the material be subjected to fre- 
quent dippings, as it will become permanently stained by so 
doing. As soon as the material has been removed from the acid 
solution, it should be immediately rinsed thoroughly in clean, 
cold water, after which it should be immersed in a bath of boil- 
ing hot water, and carefully dried off in dry sawdust. 

Cleaning Old Tinned Work 

Tinned work that has been subjected to considerable handling, 
or that has been machined, will invariably lose its luster. While 
the original luster cannot be completely restored, the appearance 
can be improved by dipping the material in a hot solution of sal- 
soda. Make the solution rather weak; a pound of sal-soda to a 
gallon of water will usually be found strong enough for ordinary 

146 



CLEANING OLD GALVANIZED AND TINNED WORK 147 

purposes, and a weaker solution should be used if it will accom- 
plish the desired result. As soon as the work is removed from 
the sal-soda solution it should be carefully and thoroughly rinsed 
in clean, cold water, and then immersed in clean, boiling water, 
after which it should be dried ofE and rubbed in dry pine saw- 
dust, to which a little flour has been added. If dry sawdust is 
not available ordinary bran will answer the purpose very well, 
provided all moisture on the work has been allowed to evaporate 
before the bran is used. 



CHAPTER XXI 

Electro-Galvanizing Plant and Equipment 

THE art of electro-galvanizing and its industry is not the 
result of an invention, but was simjDly created within the last 
twenty years by force of necessity in protecting such articles 
like springs, small wire netting, screws, bolts, nuts, etc., which 
could not up to that day be satisfactorily galvanized by the hot 
process, and this shows clearly that the creation of the electro- 
galvanizing industry was not a matter of cost. 

The cold galvanizing has its advantages, being suitable for treat- 
ing a large number of different articles, especially goods that have 
been hardened and tempered and all kinds of machine parts with 
perforations and threads ; also in the continuous processes for band 
iron, wire and the galvanizing of small articles, such as tacks, nails, 
etc., in bulk form. 

The hot galvanizing cannot compete in the satisfactory produc- 
tion of these articles, and, on the contrary, the electro-galvanizing 
never will compete with the hot galvanizing on such articles as 
tanks, boilers, architectural iron and building material, etc. 

One of the earliest records of electro-galvanizing is an English 
patent taken out by Charles Cleophas Person, on April 27, 1854, 
and reads as follows: 

Coating with Zinc by Galvanization. 

"The zincing is effected by electro-deposition from a bath con- 
taining salts of zinc and alumina. The solution may be prepared 
by dissolving precipitated alumina in a solution of sulphate of 
zinc, but the inventor prefers to dissolve oxide of zinc in a solu- 
tion of crystalized alum. The zinc may be deposited from such 
a solution on all metals, viz. : iron, copj^er, platine, etc., and the 
adhesion is complete : if care is taken previously to make the sur- 
face of the article bright." 

It is only within the past decade that any marked advance in 
the commercial use of electro-deposited zinc has been noted, and 
it is in the United States that the deposition of this metal, by 
means of a low-tension current, has reached its highest commercial 
development. While the knowledge that zinc could be readily 

148 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT Un 

deposited has existed Tor a lono; nunilxT of years, ilic ])i'0('ess was 
never taken u}) in a praetieal commercial way niitil al)oiit li)00. 
At tliat time attention was directed to the subject thron*>-h experi- 
ments made by the governments of England, Germany and the 
United States, which demonstrated the efficiency of the electro 
deposit for certain classes of work. In line witli the experiments 
M'liich liad been made, the United States Government established 
tests and installed small electro-galvanizing jdants at various 
arsenals and shij^yards throughout the country. Manufacturers 
of electro-plating materials availed themselves of the information 
))rought to their attention, and during the past ten to twelve 
years the growth of this industry has been rapid and electro 
zincing or galvanizing is now being applied to many iron and 
steel articles which could not as readily be treated in any other 
way. 

Equipment for Electro-Galvanizing Plant 

An electro-galvanizing plant may be subdivided into two im- 
portant departments — the cleaning department and the galvaniz- 
ing department proper. In the cleaning department the equip- 
ment consists of: 

1. Suitable tanks, 

a. For sulphuric or hydrofluoric pickle, 

b. For hot potash, 

c. For electro-cleaning. 

d. For washing and scrubbing. 

2. Tumbling barrels or sand blasting apparatus for cleaning 

small material. 

The galvaniziiig equipment comprises : 

1. Suital)le tanks or automatic devices, including rinsing and 

drying apparatus. 

2. Necessary galvanizing solution. 

3. Copper conductors. 

4. Anodes. 

5. Low-voltage generator. 

6. Switchboard consisting of voltmeter, ammeter and rheostat. 

7. Hot-water tank. 

This is the complete unit for a galvanizing plant with still 
tanks, and such equipment can be found in the plants of large 



150 



GALVANIZING AND TINNING 



metal maimfaeturcrs and maker.s of specialties througliout tlie 
country. Such a plant does not require any further explanation. 
A rough layout is shown in Fig. 55. 

Galvanizing is accomplished as an accessory to other' electro- 
plating activities or whole j^lants are devoted to galvanizing ex- 
clusively. Illustrations of the latter type are shown in Figs. 56 and 




m^m^>y. 



Fig. 55. Floor Plan of Electko-Galvanizixg Plant 



57. Fig. 56 shows one of the most up-to-date electro-galvanizing 
departments in tlie world, j^ossessing jjerfect light and ^■cnti]ation 
and ample room for the oioerators to discharge tlioir duties. The 
plant shoAvn is that of the Spirella Company, Niagara Falls, jST. Y., 
and is devoted to the protection of the wires of the Spirella Corset 
products. Fig. 57 shows a remarkahle electrical installation, with 
22 units supplying the current for the tanks shown in Fig. 56. 
At no point is the lead from the generator to the tank longer than' 
10 feet. 

A special feature in this plant is the covering of the cyanide 
tanks with sliding hoods, as shown on the right in the foreground 
of Fig. 56. The fumes from these tanks are taken away from 
under the hood hy an exhaust blower. 



ELECTRO-GALVANIZING PLANT ANi:) EQUIPMENT I'A 




152 



GALVANIZINC4 AND TINNING 




ELECTRO-GALVANIZING ]>LANT AND l^C^UIPMENT 153 
Mechanical Galvanizing and Patented Devices 

The foregoing pai-ag-raphs have dealt in general with electro- 
galvanizing, and, as the mechanical electro-galvanizing, in other 
words, the zinc deposition in bullv quantities, has so much merit, 
it is worthy of special mention. The increasing use of mechanical 
devices for electro-deposition aifords ample reason for an extended 
study of this juncture of the j)rinciples involved. 

In the mechanical electrical deposition of zinc, there is a higher 
voltage and amperage used, and through this in a shorter length 
of time more zinc is deposited than in still open tanks. 

Still open tanks can also ha made partly mechanical by agitating 
either the electrolyte or the goods to be plated. Some firms make 
it a practice to move the bus bar either horizontally or perpendicu- 
larly, or the electrolyte is agitated by blowing air through per- 
forated lead or ruljber tuljes from the bottom of the tanks, or ])y 
agitating the solution through a floating-tank system or by the 
means of a propeller. 

The above refers to all kinds of articles, especially such work 
which cannot be successfully plated in tumbling machinery and 
which has to be specially suspended on wires, hooks or racks. Also 
for this class of work various kinds of new machines and devices 
have been adopted to reduce the labor cost and shorten the time 
of plating. 

The Miller Chain Conveyer Machine 

Illustration 58 shows such an apparatus, patented by C. Gr. 
Miller, of the Meaker Company of Chicago. This machine carries 
the goods by means of a chain conveyer through the electrolyte. 
The chain conveyer is adjusted in a jDerpendicular position and as 
soon as one article is ready and thoroughly plated another one is 
suspended on the same hook, making the process a continuous one. 

A indicates a tank conveniently constructed of Avood, though, 
obviously, it may be lined with any suitable material. As shown, 
at the rear or discharge end of said tank is provided an upright 
frame composed of posts a — a', two on each side, and which may 
be transversely connected in any suitable manner to afford rigidity 
and strength, and journaled upon the uprights a', which are at 
the rear end of the tank, is a shaft B, provided on its outer end 
with a worm gear 6, adapted to be driven by means of a worm 



154 



GALVANIZING AND TINNING 



b^, on a sliaft h', provided witli tight and loose-belt pulleys ¥ — &■*, 
as is usual. 

Journaled upon a standard C, at the forward end of the tank, 
is a transverse shaft C^ provided centrally with a sprocket wheel 
c thereon. Journaled on adjustable pulley blocks D, of any suitable 
kind, secured on the rear end of the tank on each, side thereof is 
a shaft D\ corresponding with the shaft C^, and parallel thereto 




Fig. 58. Vertical Section of the Miller Chain Conveyer Machine 



and provided with a sprocket d centrally thereon and in alignment 
with the sprocket wheel c on the shaft C^ A corresponding sprocket 
wheel ¥' is provided on the shaft B, above the shaft D\ and trained 
about said sprocket wheels is a sprocket or link-belt chain E, of 
any suitable kind or construction, adapted to be run on said 
s|)rocket wheels. 

As shown, the diameter of the sprocket wheels c — d is such that 
the lower run of the sprocket chain E is parallel with the top of 
the tank, and, of course, with the electrolyte in the tank, and 
secured transversely on said chain at short intervals apart are metal- 
lic bars e, which are engaged to the appropriate links of said chain 
near the middle of each bar. Engaged near each end of each of 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 155 

said bars is a downwardly directed hooked wire or rod e', the lower 
end of which is directed laterally and outwardly toward the wall 
of the tank, and serve as hooks to support the articles to be 
plated or coated. 

Extending longitudinally the tank near each of the side walls 
and at the middle of the same are conductors / — /^ — -p^ which, 
as shown, are round metallic rods connected with one of the 
leads /^, from the generator F, on which are susijended the anodes 
F^, which hang downwardly in the electrolyte in parallel relation 
with each other and, of course, may be of any desired number, 
and afford a sufficient surface for the purpose required. Said con- 
ductors are connected by a cable /* with each other at one end 
of the tank. As shown, the central, parallel bus bars /^ are pro- 
vided on each side the central conductor F'-, and, as shown, are flat 
bars of' metal, which are supported upon the top of the tank and 
projecting above the same, and on which the flat bars e on the 
chain slide, and which thus serve to support the lower run of the 
chain and its load during the platnig operation. Said bus bars 
are connected with the other lead ./*' of the generator. 

As shown, the shaft D^, with its sprocket wheel d thereon, is 
arranged forwardly of the upper shaft B, and its sprocket wheel, 
thus inclining the upward run of the chain outwardly over the 
discharge end of the tank and, as shown, an inclined chute Ijoard 
Gr, is supiDorted upon suital)le brackets on the discharge end of the 
tank, and its upper end projects to near the extended ends of 
the hooks e^, as they rise from the electrolyte, and is adapted to 
receive the articles discharged from said hooks to direct the same 
from the tank. 

Means are provided for jarring the chain to shake the articles 
more or less during the plating or coating operation, and also to 
remove the coated articles from the hooks. For this purpose, as 
shown, a short shaft is journaled in suitable Ijearings on the 
inner face of each of the uprights a^ and the ends li — h^ of which 
are directed opj^ositely to i^rovide arms. The arm It, is curved to 
provide a cam, as shown more clearly in Fig. 58, and is adapted to 
be engaged by the end of each bar e, to adjust the other arm h^, 
to engage within the liook e^. Said arm h'^ is j^rovided with a 
hooked end /;-, and a spring li^ is secured at its ends to the arm 
and bar and acts to throw the hook h- outwardly when the bar e 
passes the cam /(, thcreliy removing the articles from the hooks e^. 



156 GALVANIZING AND TINNING 

Operation of the Miller Machine 

The operation is as follows : An operator stands at the receiving 
end Y of the tank and, as the chain travels downwardly toward 
the tank the current passes therethrough into the bus bars, thus 
hooks. This is, of course, easily accomplished if the articles are 
apertured. If not, wire loops may be provided whereby the article 
may be engaged upon the hook. The chain is thus loaded progres- 
sively, and as the articles are submerged in the electrolyte within 
the tank the current passes there through into the bus bars, thus 
completing the circuit. Obviously, a very large surface of the 
metal to l^e plated is exposed l^etween the anodes supported ver- 
tically in the tank, and as the articles to be plated travel longitu- 
dinally in the tank between the same the thickness of the coating 
may be regulated l)y the rate of travel and, of course, the current. 
Having passed through the tank, said articles are raised from the 
electrolyte upon the upward run of the chain and as the same 
approach the hooked jar arms h — //^ these, as the successive bars e 
engage the arm It, the arms li^ swing inwardly, after which the 
springs retract the arms h'^ for, their hooked ends to remove the 
articles from the carrying hooks, adapting the articles to fall upon 
the chute G. Owing to the quick retraction caused by the spring, 
the arm h of the jar mechanism is throAvn inwardly to engage the 
succeeding bar e, wliich jars the supporting mechanism and par- 
ticularly the lower run of the chain gently, thus tending to con- 
stantly shift the contact surface on the hook of the article being 
coated. In this manner, uniformity of the coating is assured. 

In use, the outer end of the supporting hook becomes slightly 
enlarged by the deposition thereon of the plating metal. This as- 
sists in holding the articles (while coating) on said hooks, and, in 
consequence, there is little or no tendency of the same to fall there- 
from to the 1)ottom of the tank. 

Of course, other means may l)e provided for releasing the plated 
or coated articles from the supporting hooks, the jar arms, how- 
ever, acting simultaneously and oppositely, are very effective and 
are automatic in operation. 

Obviously, the lower run of the chain is at all times supported 
in horizontal position whatsoever the load thereon, by means of the 
bus Imrs. If the chain should at any time become slack, the ad- 
justment may be quickly made by means of the adjustable bearings 
D for the shaft D\ 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT ir, 




158 GALVANIZING AND TINNING 

Daniels Screw Conveyer Machine 
Figs. 59, 60 and 61 show a similar construction by which the 
goods should be first suspended on wires, hooks or racks and then 




Fig. 60. Top Plan View of Daniels Screw Conveyer Machine 




Fig. 61. Side Elevation of Daniels Screw Conveyer Machine 



hung on a screw conveyer, fixed in a horizontal position within the 
tank above the solution. ' This device has been patented by the 
Hanson & Van Winkle Company of Newark, N. J. 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 159 

In apparatus lierein shown 10 indicates the vat for containing 
tlie hath, and 11 tlie lonuitiidinal anode rods inter-connected by 
transvei'se conductors 12 and 13. In the present embodiment of 
the invention 3 anode rods 11, comprising two outer and one inter- 
mediate, are shown. The anodes 14 are hung on the anode rods 11, 
thereby sul)dividing the entire bath into two longitudinally ex- 
tending lanes or spaces, through wliich successively it is de- 
signed to convey the articles to be phited. The numljer of lanes 
or spaces thus formed may of course be varied to suit require- 
ments, by corresponding variations in the construction of the 
ai)paratus, but the construction and arrangement herein shown 
will be sufficient to illustrate the invention. 

For conveying the articles through the spaces to either side 
of the inner line of anode rods conveyer screws 15 are provided. 
These extend longitudinally of the vat and are disposed above the 
level of the bath, one on either side of the intermediate line of 
anode plates. The conveyer screws 15 may be constructed in any 
desired manner, but as shown lierein they are constructed of 
rods or shafts, on which are disposed conveyer coils. The con- 
veyer screws are journaled at one end in suitable bearings 16, and 
at the other end on a stationary curved rod IT, as will be clearly 
shown. Intermediate of their two ends the rods are supported at 
suitable intervals by the intermediate supports or bearings 18, 
which as illustrated in Figs. 60 and 61 are bifurcated to permit 
the passage of the cathode hangers 19, as clearly shown. 

To drive the two^conveyer screws in opposite directions power is 
applied to belt pulley 20 fixed on shaft 21 suitably journaled in 
bearings 22 and carrying worm sections 23 and 21 of opposite 
pitch, which mesh with worm gears 25 and 26, respectively, of 
the two conveyer screws. A Avorm section 27 is also provided on 
shaft 21 which op)erates a worm gear 28 fixed on longitudinal 
shaft 29 journaled in bearing 30. The other end of shaft 29 
carries a bevel gear 31, which meshes with the bevel bear 32 
fixed on a vertical shaft 33, which is journaled in a bearing 31 
suitably mounted on the framework of the ajjparatus. Vertical 
shaft 33 has secured to it, as illustrated more clearly in Fig. 61, 
a transfer disk or AAdieel 35, which runs on roller bearings 3!) 
mounted in a supporting arm 37 of the framework. The sup- 
porting arm 37 provides a Ijearing or guide for the lower end of 



160 GALVANIZING AND TINNING 

vertical shaft 33 as shown. The transfer disk or wheel 35 is 
herein shown as ha^ang its periphery formed with an annular con- 
cave surface, conforming in radius with the stationary curved 
rod 17 above referred to, v;hereby the curved rod receives support. 
The curved rod serves as a transfer rod or support while, the 
cathode hangers are being transferred from one conveyer screw 
to another, as Avill be shown. The two ends of the transfer rod 
thus constituted are reduced and provided with annular peripheral 
grooves 38, forming ball races for ball bearings 39, and a pin race 
for iJie key pin 40. The adjacent ends of the conveyer screws 15 
are bored to fit over the reduced ends of the transfer rod 17, 
as clearly shown in Fig. 61, so as to bear on the ball bearings 39. 
The key pin 40 al)ove referred to is inserted through a perforation 
near the end of the conveyer screw, wherel)y the transfer rod is 
retained in position upon the transfer disk 35. 

Transfer disk 35 carries a series of radial fingers 41 which 
project outwardly from its periphery in a plane beneath the plane 
of the coils of the conveyer screws, which coils terminate within 
the vertical circumferential plane of fingers 41, but not in the 
path of the fingers. 

Operation of Daniel's Screw Conveyer Machine 

The operation of the apparatus will now be apparent. The 
cathode hangers bearing the articles to be plated are hung upon 
the conveyer screws 15 at suitable intervals while the screws are 
rotating, and the hanger thus progresses on one of the conveyer 
screws toward the transfer rod 17, passes freely through the open- 
ing at the bottom of the intermediate supporting bearings 18, 
and when it arrives at the termination of the coil on the con- 
veyer screw, it is engaged by one of the transfer fingers 41 of 
the rotary transfer disk 35. The hanger is thereby carried from 
the end of one conveyer screw onto the transfer rod 17 and 
finally delivered to the end of the other conveyer screw at a point 
where it will be engaged by the coil of the conveyer screw and 
started on its return through the bath. The negative terminal 
of the current is connected with the conveyer screws 15, so that 
the articles carried by the cathode hangers 19 become the cathode 
in the bath and are plated. The articles to be plated may be of 
such weight as to tend to distort the conveyer screws, but by the 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 101 

provision of the intermediate supporting Ijeariiigs such tendency 
is rendered inelfoctive. 

In the ap[)aratus shown and descril:»ed the articles to be plated 
are introduced and removed from the same end of the vat and 
in order to maintain the cathode surface area substantially uni- 
form in the electroplating operation, it is advisable to avoid 
variations in the number of the articles being plated. By the 
arrangement shown the maintenanc^e of uniformity in this respect 
is facilitated as the operator standing at one end of the vat in- 
troduces a new article for each plated article withdrawn. The 
rheostat can, therefore, be adjusted in starting up operations to 
suit the particular requirements, but after the number of articles 
in the vat has reached full capacity no further regulation of the 
rheostat is necessary. The plating thus conducted is of highly 
uniform character and is independent of the Judgment of the 
operator, as the conditions determining the character of the plat- 
ing are mechanically controlled. 

The Fleischer Cable or Chain Conveyer Machine 

Figs. 62 to 65 show a cable or chain conveyer traveling over 
numerous rollers and so placed that goods suspended on knobs 
fastened to the cable will travel in a continuous motion from one 
tanlv into the other. First, cleaning; second, rinsing; third, plat- 
ing, and, fourth, drying. This apparatus is patented by Herman 
& Charles Fleischer and assigned to the Stanley Works of New 
Britain, Conn. 

1 is a water-tight tank of usual form, open at the top. The 
tank 1 receives and holds the plating solution. 2, 2 are anodes. 
3, 3 are articles to be plated, which will hereinafter l)e termed the 
"cathodes." In the preferred form of our invention both the anodes 
and cathodes are mechanically conveyed into, through and out of 
said plating solution; but it is not absolutely essential to certain 
fundamental features of the invention that the cathodes themselves 
be moved through said solution. 

4, 4 are bars, which we term "anodcrcarriers," the same being 
formed of suitable conducting material. Both ends of each of the 
anode-carriers 4 are connected to drive chains or belts 5, 5, ar- 
ranged to traverse on opposite sides of the tank, each chain 5 
traversing over a series of independent guide-sprockets arranged 
on opposite sides of the machine. 



162 



GALVANIZING AND TINNING 



6, 6 are cathode-carriers, from which are suspended the cathodes 
3, 3. Both ends of each cathode-carrier are attached to chains 7, 7, 
which are arranged to traverse the opposite sides of the tank and 
are guided by suitable independent sprockets, also located on oj)po- 
site sides of the machine. 




-^ 



TOf)kiiiifiuuiiumi 



J 'd i A ^ 



7" ■ 




' in 



Fig. 62. Side Elevation of Fleischer Machine 




Fig. 63, View of 
Fleischer's Ma- 
chine Showing 
Carrier and 
Conveyeb 
Chain 



Fig. 64. Cross Sec- 
tion OF Tank of 
Fleischer Chain 
Conveyer Machine 



Fig. 65. Enlarged Detail 
View of Tank Showing 
Anodes in Position 



The chains 5 and 7 are driven at a corresponding rate of speed. 
Any suitable driving means may be provided. For example, the 
guide-sprockets 8, 8 may be mounted upon a shaft 8% so that when 
rotary motion is imparted to one of said sj)rockets it will be trans- 
mitted through one shaft to the other sprocket. One of the 
sprockets 9, traversed by chain 7, may act as the drive-sprocket for 
one of the chains 7. The corresponding guide-sprocket on the other 
side of the machine (not shown) may be mounted on a shaft with 
the guide-sprocket 9, so that when one turns the other will turn. 
The driving-sprockets 8, 9 may be connected by means of a chain 
8*", so that power applied to either of the sprockets 8 or 9 will 
be transmitted to the other. In the preferred construction the 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 103 

sprockets 8, 9 are rotated intermittently by means of a ratchet 10, 
pawl 11 and rocking arm 13. 

The anode-carriers 4 are spaced apart at equal intervals, and 
the eatliode-carriers are s])aced apart at like intervals. When the 
anodes and the cathodes are being conveyed through the solution 
in the tank 1 it is preferred that said anodes and cathodes be 
spaced apart alternately and at equal intervals. 

13, 13 are tracks along the upper opposite edges of the tank 1 
and arranged to support the anode-carriers 4 while the anodes are 
immersed in the solution in tank 1. 14, 14 are tracks also ar- 
ranged along the edges of the tank 1, their function being to sup- 
port the cathode-carriers 6 when the cathodes are immersed in the 
solution. To prevent interference, tlie tracks 14, 14 are prefer- 
ably spaced apart a less width and are at a loAver elevation than 
the tracks 13. The length of the cathode-carriers G is corre- 
spondingly less than the length of the anode-carriers 4. One or 
both of the tracks 13 constitutes electrical contact for the carrier 4. 
The same is true of one or both of the tracks 14, the same being 
an electrical contact for the cathode-carrier 6. The signs plus (-|-) 
and minus ( — ) represent the respective electrical connections. 
The track 13, being the anode connection, is positive, while the 
track 14, being the cathode connection, is negative. 

The chains 5 and 7 are preferably insulated from the carriers 
4 and 6. 

15 is a bushing of insulating material provided at each end 
of the carriers. Pins 5", carried by the chain 5, project into these 
insulating-bushings 15. 

The guide-sprockets over which the anode-chains 5 run are so 
arranged that the anodes will be lowered into the plating solution 
at one end of the tank, whereupon the anode-carrier will make elec- 
trical connection with the track 13. The anodes are then con- 
veyed through the solution and removed from the other end of 
the tank. The guide-sprockets over which the cathode-chains 7 
run are so arranged that the cathodes will be lowered into the 
solution alternately with the anodes, whereupon the cathode-carriers 
will make an electrical connection with the track 14. The cathodes 
are then conveyed through the plating solution and removed from 
the other end of the tank. While in the solution the cathodes and 
anodes are preferably spaced apart at equal intervals. While in 
the jDlating solution the surfaces of the anodes will l^ecome fouled 



164 GALVANIZING AND TINNING 

by a scum-like deposit, which if allowed to accumulate will impair 
the free plating action and dissolution of the metal. By making 
the anodes automatically removable they may be readily cleaned — 
for example, by causing them to )}e immersed in an anode-cleansing 
bath, which may be provided in tank 15. The guide-sprockets 
16, 16, 17 are so arranged that each anode will be lifted up over 
the edges of the tank 15 and immersed for a short time in the 
cleansing solution therein. There are many advantages in keep- 
ing the anodes clean, among which are rapidity of dissolution of 
the metal, relatively rapid speed and uniformity of deposit, saving 
in electric current and chemicals. The balance of "the guide- 
sprockets for the anode-chain not already numbered are indicated 
at 18, 18. Obviously the particular arrangement of the guide- 
sprockets and the method of supporting them is entirely immaterial. 
The movement of the chains 5, 7 is so comparatively slow that 
an operator standing at either end of the tank may remove the 
plated articles from the cathode-carriers 6 and substitute unplated 
articles which in due course will be conveyed through the plating 
solution, as previously described. 

By causing the articles to be passed through the solution alter- 
nately with the anodes, each line of articles suspended from a 
cathode-carrier is moving into a sphere of solution which has been 
enriched by the dissolution of the anode immediately in front of 
it, the said anode practically recharging the solution which has 
been partially impoverished by the cathode immediately preceding 
said anode. 

While to those features of the invention already descril)ed it is 
not essential that the apparatus shall have the capacity of pre- 
paring the articles to receive the plating deposit, a further de- 
velopment of the invention contemplates the continuation of the 
cathode-chains 7, 7 so that they will cause the cathode-carriers 6, 6 
and articles suspended therefrom to traverse a washing-tank 19, in 
which tank various baths may be provided in separate compart- 
ments, into which the articles to be plated may l)e successively 
immersed in order to prepare the surfaces thereof to receive the 
plating solution. We have found that great economies are at- 
tained by this arrangement. Kot only is the danger of possible 
contamination of the surface of the article rendered practically 
impossible, because the articles are not manually handled after 
being cleaned and until they are plated, but a decided saving in 



ELECTRO dALVAKTTZTNG PLANT AND EQUIPMENT 16r, 

chemicals results. Tlio cliains 7 traverse in the direction of tiie 
arrows, so that an oj)erator standing at the lel't-luind end of tlie 
tank may attach to the carriers mounted on the chain 7 the articles 
to be plated. These articles are conveyed into the several prepara- 
tory baths successively, and the movement is so comparatively 
slow that ample opportunity is given for the chemicals to drip from 
the articles into the baths from which they are removed before being 
immersed in another bath which may be, for example, of a different 
chemical nature. This drip occurs directly over the bath from 
which the article is removed, and hence the particular chemicals 
therein are saved. 

The danger of injury to operatives by contact with the chemicals, 
incidental to the cleansing of the articles, is entirely eliminated. 

20 is a final washing-tank at the opposite end of the plating- 
tank into which the plated articles are immersed after being re- 
moved from the plating solution. 

21, 21 represent the sprockets for the chain 7 whereby said chain 
is moved in such a course that the cathode-carriers supported by 
said chain will be conveyed in such a direction as to move the 
articles to be plated over each of the partitions in the tanks 19 
and 20, so that the said articles will be washed or immersed in 
the aforesaid baths. The particular arrangement of these sprockets 
21 is, of course, immaterial so long as they permit of the use of 
endless bands or belts 7. 

These foregoing illustrations show the different ways and means 
which can be adopted to improve the plating of larger articles 
in open-tank work. 

The Daniels Plating Barrel 

Pigs. 66 to 69 show a plating barrel suspended on a shaft 
with a special connection carrier. The barrel is of the perforated 
type and is immersed entirely in the solution. Curved anodes have 
to be used to secure a better current conductively all around the 
barrel. The center shaft within the barrel is provided with chains 
to connect the work with the negative current of the dynamo. By 
loading and unloading the goods to be plated in this barrel, the 
barrel must be lifted from the solution and connections by means 
of a lifting device. This machine is patented by the Hanson & Van 
Winkle Company of Newark, N. J, 

Fig, 68 is a longitudinal vertical section of one form of electro- 



166 



. GALVANIZING AND TINNING 



plating apparatus, and one form of revoluble container, clrnm or 
cylinder, mounted upon a shaft or spindle, said view illustrating 
in elevation, a number of flexible contacts or cathode-elements em- 
))odjing the principles of this invention. 

1 is the tank, comprising base 2, sides 3 and ends 4. 5 is one 
of tlie two usual and similar anode bars from wliicli the anodes 5' 
are suspended on cither side of the drum or contaiiu'r 8. These 
bars 5 are secured to tlic tank bv fasteners, as C). and are con- 




FiG. 66. Hand Wheel Lifting Device fok Daniels Barkel 



nected by means of the connector 7 with the wire 7', which connects 
with the positive terminal of an electric generator. 

The mass of articles 8' is placed within drum 8, which is rigidly 
mounted on shaft 9, rotatable in bearings 11 of removable suspen- 
sion frame 10 having members 12 removably engaging Avith and 
supported by rods 13 secured to and extending across tank 1, and 
through connector 13' and wire 13" connected with the negative 
terminal of an electric generator. Shaft 9 is driven from a shaft 
member 14 by any convenient power, a separate connection between 
said shaft and member being made, in this instance. 



ELKCTRO-GALVANrZTNG TLANT AND EQUIPMENT 167 

The nov(-'l cathotlc members, or elements, are Icxjsely and movalily 
coml)iiu'(l with and su})ported by shaft i), from wliich tliey (k'[)('iid. 
Tlu'y coiuitiisi', in tliis instance, a weight or sinker-])ortion 11), a 




Fig. 07. Lkveu Lifting Jjevick h\i. Da.mels Barrel 



J^7^ '^ 




Fig. 68. Vertical Section of Daniels Plating Barrel 



coupling portion comprising ring, or eye, 16 loosely encircling shaft 
9, and an intermediate flexible portion, in this instance a section 
of chain i8, the upper link of which is connected with an eye or 



168 



GALVANIZING AND TINNING 



hook-shaped part 17 of a stem or rod 15, therehy loosely con- 
necting 15 with 19 as shown. 

During the rotation of the drum the articles to be electroplated 
are tumbled about within said drum, constantly exposing new sur- 
faces, and making efficient contact Avith the weight or sinker-portion 
19 of the cathode-meml)er. 




Fig. 69. Transverse SECTIO^- of Daniels Plating Barrel 



The Potthoff Automatic Galvanizing Barrel 

Figs. 70 and 71 show an apparatus patented by Louis Potthoff, 
of the United States Electro Galvanizing Co. of Brooklyn, N. Y. 
Fig. 70 shows that the plating barrel is resting in bearings 
and center shaft on top of a plating tank, immersing the plat- 
ing barrel only about one-third into the solution. It also is pro- 
vided with inside anodes supported through a center shaft and 
special anodes supports to prevent the articles from coming in con- 
tact with the anodes. After the articles have been plated the spring- 
door is set and the goods will be discharged little l)y little into 
Hie washing drum and carried from here in a screw conveyer into 
the drying drum and then finally into a tray. 

The tumbling barrel 1 is mounted on a shaft supported on the 
solution tank 2 by bearings 3. Tumbling barrel 1 is rotated by 
means of sprocket 4 and chain 5. On the opposite side of barrel 1 
is a sprocket 6 with driving chain 7, which actuates the sprocket 8 
on one end of shaft 9, shaft 9 being journaled in bearing 10, sup- 
ported on tank 2. Shaft 9 is provided with bevel bear 11, meshing 



KUXTIIOCAIA'AXIZIXO PLANT AND EQUIPMENT IC!) 

witli ,u"(':ir I'i |)i)sili()ii('(l at (nic end of sliai't 13. Slial't l^) is ])!■()- 
vi(k'<l with a hearing 11 in proximity to gear 12. JMoimted ujxjii 
.shaft 13 are the washing drum 15, draining drum 16, and drying 




Fig. 70. Potthoff Automatic Galvanizing Barrel 

drum 17. Shaft 13 is preferably slightly inclined to assist the 
progressive movement of articles treated in washing drum 15, drain- 
ing drum 16, and drying drum IT. 

When the tumbling barrel 1 is rotated in the direction of the 
arrow 18 the contained material is subjected to the combined 
tumbling and plating treatment, and at the same time the devices 
for subsequent mechanical handling of the material are operated 
to progress the material through the various operations and finally 
sorted and collected in a suitable receptacle for shipment or storage. 

Tumljling l)arrel 1 comprises a barrel having its inner periphery 
covered witli porous material, preferably cocoa-matting 21, upon 
which strips 20 are placed, in which strips 20 there are provided 
holes of such size as to prevent the articles treated in barrel 1 from 
projecting therethrough. For the cocoa-matting covering are 



170 



GALVANIZING AND TINNING 



claimed many advantages over material heretofore employed for 
this purpose, for by means of cocoa-matting the articles are given 
a high polish, and no obstruction is offered by the cocoa-matting 
to the passage of the electric current. Strips 20 may be made of 
wood or other insulating material. The barrel 1 is supported on 
tank 2 by means of spiders 22 joined to shafts of sprockets 4 and 
6, respectively. 




.'/////////^/y^^////y A d- / ///// /////// //////////^/ ////// /ZT77777\ 



Fig. 71. Section of Potthoff Automatic Galvanizing Barrel 



Within barrel 1 a pocket 23 is formed by extending across the 
barrel an inclined plate making an angle with the curved side of 
barrel 1, and a jDivoted, automatically actuated door 24 closes the 
opening at the end of pocket 23. As shown, the pocket 23 extends 
transversely across barrel 1, opening within said barrel so that 
when said barrel is rotated in the direction of arrow 25 articles 
will be caught by pocket 23 and will be in a position to be dis- 
charged upon the automatic opening of door 24. Door 24 is pro- 
vided with springs 26 and latching devices whereby to automatically 
open the door upward when the latching devices are tripped. 

On the ends of barrel 1 are pivoted latches 27 controlled by 
springs 28. Latches 27 co-operate with pins 29 on the door 24, 
so that normally latches 27 hold the door 24 in closed position 
against the tension of springs 26. 

Supported by standards 30 on tank 2 are pivoted tripping fingers 
31, one end of each finger 31 co-operating with each of the latches 
27, the other end of each finger 31 being weighted and further 
provided with a lug 32 contacting with standard 30 to maintain 
normally each finger 31 in a horizontal position and preventing 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 171 

further rotation in the counter-clockwise direction. When barrel 
1 is rotated in the direction of arrow 18 the latches 27 will depress 
the fingers 31 without l)eing tripped, but upon reversal of rotation 
in the direction of arrow 25 fingers 31 will trip latches 27, alloAv- 
ing the door 24 to open automatically and permit material caught 
in pockets 23 to be discharged from barrel 1 outside the plating 
tank. 

Mounted on tank 2 on the opposite side are stationary cams 33, 
which are engaged by pins 29 to close and latch the door 24. 
This occurs upon continued reverse rotation of the plating barrel, 
and the door will again automatically open to discharge a further 
quantity of material caught by pocket 23 when the latch 27 is 
again tripped. 

Chute 34 is pivoted on funnel member 35, which is mounted 
on washing tank 36 by means of arms 37. 

Washing drum 15 is composed of perforated material mounted 
on shaft 13 by means of a spider 38. At one end there is an 
opening registering with funnel member 35, and at the opposite 
end is a pocket 39 positioned so that articles contained in the 
drum when rotated in the direction of the arrow 19 will be caught 
in pocket 39 and discharged into the draining drum 16. Draining 
drum 16 is preferably connected with washing drum 15, and, as 
shown, may be similarly constructed of perforated material. 

Connected with draining drum 16 and having an opening re- 
ceiving the discharge from pocket 39 is the drying drum 17, which 
may be supported, by a spider 41. The drying drum 17 may be 
formed of perforated material, and with an outer covering of 
asbestos or similar material. Drying drum 17 is preferably pro- 
vided also with a stationary housing 42. 

43 is a heater disposed below the drum 17, shown as a plurality 
of gas jets, but obviously any other type of heating means may 
be employed. Drying drum 17 is further jDrovided with a com- 
bined discharging pocket and chute 44, which pocket 44 is so 
positioned that articles are caught therein at the bottom, and dis- 
charged at the top, when the drum is rotated in the direction of 
the arrow 19. 

The washing drum is of such diameter or so positioned as to 
be partially immersed in the washing liquid in tank 36, which 
washing liquid may l)e continuously replenished l)y means of suit- 
able supply and discharge pipes. The draining drum 16 is of 



172 



GALVANIZING AND TINNING 



smaller diameter than the washing drmn 15, and, preferably, one 
end of draining drum 16 bears upon the upper side of tank 36, 
the bearing friction being relieved by anti-friction roller devices 45 
eo-opcratiiig with a bearing ring 46 on draining drmn 16. 

The Schulte Mechanical Galvanizing Barrel 

Illustration 72 shows a plating machine resting and travel- 
ing on two rings, one acting as a gear and the other as a current 
connector. It is substantially constructed of 2-in. cypress. The 
standard size l)arrel is 36 in. in diameter and 12 in. wide, resting 
in a tank 53 in. long, 21 in. wide and 33 in. deep (inside measure- 
ments). 




Fig. 72. Schulte Mechanical Galvanizing Barrel 

The apparatus is also constructed so as to allow a large amoiuit 
of anode surface within the drum witliout interfering with the arti- 
cles to be plated ; doing away entirely with the necessity of perfora- 
tions, making it possible to plate successfully the smallest articles 
such as needles, pins, rivets, screws, etc. Tlie drum in traveling 
(Uockwise subjects the articles thoroughly to the action of the elec- 
tric current, thus plating evenly. 

The most important features of this new a})paratus are the 
methods of loading and unloading of its contents. These are 
shown in Figs. 73 and 7'4. 

The lid is removed from the drum and tlie loading of the articles 
is done as shown in the illustration, without removing the drum 
from the solution and disconnecting it from the plating current. 



KI.ECTRO-GALVANFZINr; TLANT AND KQT'I I'M KN'I' 173 

Tlio unloading of iln' ;u'ticl(,'s plai(!(l IVojii ilu! druin is done in 
tlic siniplcsi niiuiiicr. 'I'lic itcrforatcd carrier is insf!rt(Hl in the place 

of the lid and in (uic rcNoliil ion oT the drum is filled. M'liis opera- 




FiG. T.i. Loading Schulte Barrel 




Fig. 74. Uni.oaojng (!aj-vamizkij Auticjj<;s ikom Schulte Bakuel 



174 



GALVANIZING AND TINNING 



tion is repeated until the entire finished plated articles are removed 
leaving the solution intact in the drum and ready for repeated use. 

The Ele-Kem Galvanizing Barrel 

A saw-toothed barrel lining is the chief feature of this construc- 
tion. The object of this is twofold. First, that the articles to be 
plated may be thoroughly subjected to the action of the electric 
current. As the barrel rotates from left to right, it will be noted 




Fig. 75. Side View of Ele-Kem Barrel when Used as a Dryer 

that the load is carried successively on these saw-teeth and when 
reaching the half turn, the load is shoveled over so that every part 
of the mass to be plated is presented to anodic action. 

The saw-tooth construction has, however, a second mission equally 
important to the first, in that it does away with the necessity of 
removing the barrel for the discharge of its contents. It will be 
seen tkat as the barrel rotates from left to right, when the action 
is reversed, a part of the plated mass is carried uj) on the angle 
of the saw-teeth and is discharged on a receiving trough or chute. 
The continuance of the rotation insures the depositing of the 
entire plated load down to the last rivet, screw or buckle. From 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 



175 



the trough, which receives the articles so deposited, the load is 
raked by the operator or the slope of the trough can ]je so ad- 
justed as to carry the load out by gra\ ity. 

The barrel construction can be used hy modifications of its form 
for the purposes of plating, burnishing or drying. Tlie Itarrcl is 
substantially constructed of 2-in. cypress or oak, as desired. The 
standard plating barrel is 3 ft. in diameter and 3 ft. in length. 
It has a 11-inch opening in the fron!; through which the goods 




Fig. 70. Details of Ele-Kem Baruel 



arc charged and discharged. In the standard barrel there are eight 
saw-tooth steps. -These thorouglily mix the articles by the shovel- 
ing process referred to and effectively prevent their sliding en masse. 
The barrel rests in a tank 2 ft. deep, 3 ft. 6 in. in length and 
3 ft. 6 in. Avide and is driven by a worm and gear with a reverse 
pulley. When the a|jparatus is running clockAvise, the articles are 
plated and, l)y reversing the movement by means of the shasfting 
l)elt, the goods arc unloaded, as previously descril^ed, on a per- 
forated chute. The goods can be raked or shoveled into a con- 
tainer, pail or tray, from which they can be transferred to the 
hot water or into a drying machine. 



176 



GALVANIZING AND TINNING 



In addition to the outside anodes, there is an inside, adjustable 
flat anode hooked to the hollow, central shaft, both connected and 
renewed. The means of connection are novel. The shaft is hollow 




Fig. 77. Section Showing Sawtoothed Lining of Ele-Iveji Barrel 



and through it runs a copper rod insulated l)y a ruljber hose and 
an extension from this rod leads into the solution on the inside of 
the barrel and makes connection with the goods to he plated. 

In Fig. 75 will be noted the barrel adapted for drying purposes. 
It is made out of perforated galvanized sheet metal and installed 
in an iron tank holding hot water. The l)arrel is driven by a 
sprocket wheel and a belt on a small shaft. The goods to be 
dried are placed at the rear opening of the drum and are ele- 
vated in the course of rotation and discharged through a per- 
forated cylinder extending in front of the drum, and thence into 
a suitable container. In handling castings or any other material. 



ELECTRO-CALVANIZING PLANT AND EQUIPMENT 



177 



the hot water is sufficient to l)riiig about a satisfactory drying. For 
small, light articles or stampings, a steam coil is placed beneath 
the extended cylinder. In special cases a compressed air supply is 
delivered to the inside of the drum and forced through the goods, 




Fig. 78. Details of Lining and Shaft Connections 



thus insuring al)Solute drying and doing away with the necessity 
of using sawdust, etc. 

This machine is patented by Louis Schulte and sold by the Ele- 
Kem ComjDany of Chicago. 

A Cleaning. Rinsing and Plating Barrel Unit 

Figs. 79 to 84 give a view and details of a plating l)arrel of 
a smaller type so constructed that it easily can he removed from 
one tank into another and thereby allow the cleaning, rinsing and 
plating to be done Avithout removing the articles from the barrel 
from the start until the complete process is accomplished. The 



178 



GALVANIZING AND TINNING 



plating container or barrel travels on a ring fastened through 
spokes to the walls of the barrel and the ring travels on a small 
sprocket wheel, set in motion by a belt or little motor. This 
machine is patented by Louis Schulte of Chicago. 

By the system of cleaning, rinsing and plating without handling 
the articles, it not only reduces time lost in preparing articles to 
be plated, but increases the output with less labor. 

The mechanical plating barrel, as shown by the accompanying 
cut, has three wooden tanks with a rotating shaft on each one; 
on the end of this shaft is mounted a sprocket wheel which en- 
gages with the carrier ring supporting the basket or barrel. 




Fig. 79. Front View of Complete Plating Unit 



The carrier ring, being perforated to engage the teeth on the 
small driving wheel, insures a positive drive. 

The three rotating shafts are connected by means of sprocket 
wheels and chains, which are driven by motor or belt from first 
tank. 

Fig. 82 is a top plan view of an electroplating device embodying 
a modified form of the machine. Fig. 83 is a vertical longitudinal 
section of the device shown in Fig. 82. Fig. 84 is a vertical trans- 
verse section taken on line y — ij of Fig. 82. 

The preferred form of construction, as illustrated in the draw- 
ings, comprises a tank 1 formed of non-conductive material, said 



SlLECTRO-GALVANIZlNG PLANT AND EQUIPMENT 



170 



tank being open at its upper side. Arranged at the upper edge 
of the tank 1 is a shaft 2 which is mounted in suitable bearings 
3 and 4. Provided at the outer end of the shaft 2 is a pulley 
5 adapted for engagement by a belt in rotating the shaft 2. Pro- 
vided at the inner end of tlie shaft 2 is a gear 6. The gear G 
meshes with an annular internal gear 7, which depends therefrom 
into the tank 1 as clearly shown, the gear 7 resting loosely upon 
the gear 6, the same being held in mesh with said gear 6 through 




Fig. 80 — Vertical Transverse 

Section 



Fig. 81 — Section Showing 
Container 



gravity. The opposite sides of the gear 7 are provided with in- 
wardly extending flanges 8, which serve to hold said gear in mesh 
with the gear 7, a channel being thus formed. Surrounding the 
outer side of gear 7 and the corresponding sides of flanges 8 is a 
covering 9 of insulating material, preferably rubber. With the ar- 
rangement disclosed it will be seen that upon rotation of the 
shaft 2 gear 7 will be propelled thereby, the latter being caused 
to rotate in the tank 1, as will be readily understood. 



180 GALVANIZING AND TINNING 

Arranged centrally in the gear 7 is a holder or container for 
the articles which it is desired to plate. This holder comprises a 
hollow foraminated body 10 of non-conductive material such as 
wood, and a conductive frame formed preferably of metal, which 
consists of the annular angular members 11, which are arranged 
at the opposite sides of the body 1 and connecting bars 12 which 
extend between the members 11 at intervals. The members 11 
and 12 are so arranged that surfaces thereof will be exposed to 
the interior of the holder container and so that in use articles ar- 
ranged in the body 10 will contact with said surfaces and thus es- 
tablish an electrical connection between said articles and the frame 
of said body. Said body frame is rigidly secured to the gear 7 
through the medium of radiating bars 13 also of conductive ma- 
terial, and so that in use the electrical current passing through the 
goods contained in the holder will pass through the frame mem- 
bers 11 and 12, through the arms 13 and thence through gear 7 and 
gear 6 meshing therewith to the shaft 2 to complete the electrical 
circuit as hereinafter described. 

A section 14 of the peripheral wall of the body 10 is slidal)ly 
mounted in order to constitute a door for gaining access to the in- 
terior of said body, the lateral edges of the section 14 being in dove- 
tail connection with the adjacent edges of said body, the frame 
member 11 at one side being cut away as at 15 in order to afford 
clearance for said section as will be readily understood. The door 
section 14 is releasably secured in closed position through the me- 
dium of a suitable locking device 16. The inwardly extending 
flanges of the frame member 11, at the opening which is formed 
upon removal of the door 14 are cut away. 

Arranged in the tank 1 adjacent the upper edge thereof and at 
either side of the holder or container are bars 17 from which de- 
pend anode-forming electrodes 18. Upon bearing 3 and corre- 
sponding extremities of the bars 17 are binding posts 19 and 20 
respectively for connecting the same with a source of electrical 
energy. The circuit which is thus formed includes the frame 
members 11 and 12 of the holder or container which form cathodes 
and the electrodes 18 which constitute anodes, said electrodes be- 
ing electrically connected in order to close the circuit by the elec- 
trolyte which is introduced into the tank 1 in the electroplating 
process and the articles arranged in holder for plating. 



ELECTRO-GALVANIZING PLANT AND F.QUIPMENT 181 

Operation of the Plating Barrel 

First, place the artit'les to he plated in the rotating hasket. 

Second, suspend hasket on rotating sprocket on cold electric 
cleaning tank foi' a suHk-ient length of time to clean the work. This 
depends upon the condition of the same and may require from 
five to fifteen minutes. 

Third, transjjose the hasket from cleaning tank to the rinsing 
tank, letting the hasket rotate in the rinsing tank for a period of 
two to three minutes. 

Fourth, then transpose the hasket from the rinsing tank to the 
plating taidc — allowing it to rotate therein long enough to ohtain 
a plate sullicient for the requirements. 

A plate may be ol)tained in fifteen to twenty minutes that will 
stand buffing without cutting through. 

After removing articles, they are dried in the usual way. 

In o])erating the device, the articles which it is desired to plate 
are first introduced into the holder or container body 10 through the 
door 14. If it is desired to clean the articles before electroplating, 
a cleansing liquid is introduced into the tank 1 and the container 
revolved therein through operation of the shaft 2. After cleansing 
and rinsing of the articles the container is placed in another tank 1 
in Avhich an electrolyte is provided or if desired the same will be 
permitted to remain in the tank 1 from ^^'llich the cleansing liquid 
has been removed and into which the electrolyte has been intro- 
duced. The container is then rotated as before in the electrolyte. 
When this is done it will l)e seen that the articles resting in con- 
tact with the frame members 11 and 12 of the container body will 
become the cathode in the electrical circuit to which the current 
will flow through the electrolyte from the anode-forming elec- 
trodes 18, thus effecting the plating of said articles as will be 
readily understood. After the articles have thus been plated the 
container may lie removed from the tank 1 by disengaging the 
gear 7 from the gear G, such disengagement being readily effected 
since the gear 7 simply rests upon the gear G as above described. 
After the coat or plating has dried upon the articles, the container 
may be rotated as before in the empty tank 1 in order to effect 
burnishing or polishing thereof, it being clear upon rotation of 
such container the articles will rub against each other and thereby 
polish the same as desired. 

It is thus seen that with the construction set forth, the entire 



182 GALVANIZING AND TINNING 

electroplating j^roeess may be carried on without necessitating the 
removal of the articles treated from the container in which the same 
are arranged at the commencement of the treatment, the -articles 
being removed from said container onl}- upon completion of the elec- 
troplating. This is rendered possible by reason of the detachal)le 
arrangement of the container in the tank, said container, where a 
plurality of tanks are used in the process, being simjDly removed 
from one tank and placed in another as will be readily understood. 
Further with this construction the loss of electrical energy is ob- 
viated, since witii tliis construction the circuit is closed upon the in- 
sertion of the container in the tank or when gear 7 contacts with 
the gear 6 and broken when said container is removed from the tank 
or when the gear 7 is disengaged from the gear 6, the circuit lieing 
thus closed only when the container is in operative position. Also 
with this construction the necessity of a hand operable switch is 
dispensed with since the breakingand closing of the circuit is auto- 
matically effected upon removal or insertion of tlie container in the 
tank. 

Numerous other advantages of the construction which it is not 
necessary here to mention will l)e apparent to those skilled in the 
art. 

A Modified Form of the Cleaning, Rinsing and Plating 
Barrel Unit 

Figs. 82 to 84 show a construction which is a slight modification of 
that just described. In this construction the container 10 is longer 
than that of the preferred form and at each end of said container is 
provided a gear 7 and the parts which co-operate therewith to which 
the respective ends of said container are connected in the same man- 
ner as the gear 7 is connected Avith the container body 10 in the 
preferred form. The gears 7 of the modified form mesh with gears 
21 which are provided at the respective ends of a shaft 22 which is 
mounted in suitable bearings 23 provided upon cross pieces 2-1 which 
rest loosely upon the upper edges of opposing walls of the tank. The 
arrangement is such as will be observed that upon rotation of the 
shaft 22 the container 10 depending therefrom will be rotated in 
the same manner as the container 10 of the preferred form. The 
removal of the container in the modified form, however, is effected 
by engaging the opposite ends of the cross pieces 21 which are 
formed into grips or handles as shown for this purpose. Rotation 



KLKOTIRO-GALVANIZING PLANT AND lOiiUU'MHNT l8:i 

of tho shaft 22 is socurod tliron.u-li the iiiodium of a o-car 25 whicli 
is fixed to said shaft midway the ends thereof. The gear 25 meshes 
with a gear 2G provided u]x)n a shaft 27 which is momited at the free 
end of a rot'king hearing arm 28, the opposite end of said arm 28 
])eing fulcriimed to a shaft 2!) which is mounted in l)earings 29' pro- 
vided at the upper edge of tlie tank 1 as shown in Figs. 82 and 84. 
Tlie shaft 27 is operatively connected with the shaft 20 through a 
helt 30 whicii passes around ])ulleys 31 provided upon said shafts 



Fig. 82 — I^lan of Modi- 
fied Form of the 
Barrel and Tank 




Fig. 84 — Transverse ~m ■ 
Section of the Bar- 
rel and Tank 



1 



jiS' 



Fig. S3 — Vertical Section of Modified Form 
OF the Barrel 

as shown. Tfie shaft 29 is also provided with a pulley 32 for con- 
nection thereof hy means of a belt 33 with any suitable source of 
power supply. With the arrangement disclosed it will be seen that 
the gear 26 rests loosely in contact with the gear 25, said gears be- 
ing held in mesh by the weight of the gear 26 and the bearing arm 
28, and so that when it is desired to remove the container 10 said 
arm 28 may be rocked upwardly and outwardly to disengage the 
gear 26 and permit of lifting of the container out of the tank. The 
operation of this construction is precisely the same as that above 
described, anode-forming electrodes 18 being used, which are, how- 
ever, arranged along the lateral wall or sides of the container 10 
instead of at the ends of the container as shown in Figs. 80 and 81. 



184 



GALVANIZING AND TINNING 



The Meaker Continuous Type Machine 

Figs. 85 and 86 show a machine of the continuous type fixed 
with horizontal anodes and a rocking device for supplying or load- 
ing the machine. From tlie rocker the goods are conveyed over a 
perforated tray, connected with the negative current. This tray is 
continuously rocking or shifting in a downward horizontal position 

Fig. 85. Top Plan of Meaker Continuous Type Machine 




Fig. 86. Side Elevation of Meaker Continuous Type Machine 



and will finally deliver the plated goods onto an unloading tray into 
the rinsing tank. This machine is the patent of G. L. ]\Ieaker of 
Chicago. 

In said draAvings: A indicates a tank for the electrolyte. Said 
tank may of course be of any suitable size, form or material, but as 
shown, is an elongated rectangular trough constructed of wood or 
any material not adapted to injuriously affect or be affected b}' the 
electrolyte. B indicates a transverse shaft or rod extending through 
the sides of said tank somewhat above the bottom and affording con- 
nection for one of the conductors from the generator B' or other 
source of current. Slidably supported near its lower or discharge 



ELECTRO-GALVAKIZING PLANT AND EQUIPMENT i«5 

end on said shaft B is a frame C comprising parallel side rails c and 
iiu upper end rail c\ Extending transversely beneath and connect- 
ing said side rails c, are l)ars c'-, which are rigidly bolted through 
the side rails c, as shown in Figs. 85 and 86, and on which, adjacent 
each of said side members c, and extending longitudinally the 
frame, is secured a conductor c^, comprising a sheet or plate of 
suitable metal. Eesting in said frame and upon said conductors 
c% is a tray D, comprising as shown, side rails d parallel with the 
side rails c, of the frame, and an end rail d}. The bottom of said 
tray comprises a sheet or sheets of metal d~, conveniently copper, 
which, to limit the exposed cathode surface, may be lined on the 
upper side with insulating material d^, through which project me- 
tallic pins d*. These are shown as rivets, rigidly secured in the 
sheet metal bottom of the tray and the heads of which protrude 
above the lining, but of course a non-conducting bottom may be 
used and straps or bars of metal inserted m its upper surface and 
connected with the conductors. Said tray is rigidly secured to the 
side members c of the frame by means of plates d^, which are bolted 
to the rails c and engage over the side members d of the tray. The 
forward or receiving end of said frame and tray are supported at 
an elevation above the discharge end For this purpose, as shown, 
a bracket E is rigidly secured upon each of the side walls of the 
tank at the front end thereof and at its upper part affords bear- 
ings for a transverse shaft e, on which are journaled jar bars E\, 
one for each side of the frame C Rigidly secured on the forward 
end of said frame approximately m alinement with the side rails c, 
are forwardly projecting arms or brackets c*, through the forward- 
ly projecting ends of which extends a shaft e^ which also extends 
through the lower ends of the jar bars 

Journaled transversely, on the rear sides of the brackets E, at 
the top of the tank is a driving shaft E^ which is provided at one end 
with a driving pulley e-, adapted for engagement l)y a suitable driv- 
ing belt and at its opposite end with a suitable pulley or sprocket 
wheel (in this instance shown as a grooved pulley), e^, adapted to 
drive an elevator to deliver the plated articles from the machine. 
."Rigidly secured on said driving shaft E' are cams e^ one opposite 
each jar bar as the driving shaft rotates, drawing the frame and 
tray forwardly, and is shaped to afford a quick release at the for- 
ward limit of movement of the jar bar. For this purpose the op- 
posite or release side for said cam projection is abrupt, and to fur- 



1S6 C^AtVANlZlt^G AKD TINNma 

tlier effect quick release, the lower rear side of each jar bar is cut 
away just below the point of contact with said cam so that when 
pressed forwardly to its limit of travel^ immediate and complete 
release follows, permitting the jar bars with the attached frame 
and tray to swing longitudinally the tank. As shown a shaft F, 
extends transversely through the tank and secured thereon are 
strong pulling springs f, attached at their ends respectively to the 
jar bars and to said shaft and which act to snap the frame and 
tray toward the rear after each slow forward movement. Pivotally 
engaged on said shaft F is the receiving chute f-, the upper end of 
which rests on the periphery of said cams and is somewhat wider 
than the frame and tray. The lower end thereof projects over the 
tray and tapers to slightly less than the width of the tray to insure 
the delivery of the articles to be plated across the entire width of 
the tray. As shown a strong pulling spring /^ is secured on the end 
of said chute above the cams and extends obliquely downward and 
is attached to the end of the tank as shown in Figs. 85 and 86, thus 
holding the ujDper end of the chute firmly on the cams. Said cams 
act to rock said chute on its shaft F, and as the projections e^, on 
the cams pass from beneath the chute, the spring p pulls the end 
thereof down upon the cams constantly, jarring the chute and spill- 
ing the contents into the tray. 

Rigidly secured on the under side of the frame C are metallic 
shoes c*' which bear on the shaft B and are of a length to permit 
the longitudinal reciprocation of the frame and tray before de- 
scribed and are conveniently provided at their front ends with hooks 
c'^, which extend beneath the shaft B. Butting blocks G are bolted 
one on each side of the tank and projecting inwardly into position 
to afPord stops for the frame and tray at the rearward limit of move- 
ment. The frame rails c are each provided with a stop g bolted 
on its rear end in position to abut the butting block G at the rear- 
ward limit of movement to suddenly stop the frame and tray when 
snapped back by the springs. 

, Journaled in suitable brackets H on the rear end of the tank is 
a shaft //, having on its outer end a grooved pulley Zi^, adapted to 
receive the driving line or belt Ir, trained around the grooved pul- 
ley e^ on the driving shaft E-. Journaled transversely in the tank 
near the bottom thereof and parallel the sliafts li is a shaft H^, and 
trained about said shafts h and IP is a conveyer belt h^ having 
buckets /i* rigidly secured thereon by riveting or other suitable 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 187 

means. Each of said buckets is perforated in its bottom to permit 
the escape of the electrolyte and may be constructed of sheet metal, 
fiber or any suitable material. 

Journaled on the shaft B is a discharge chute I, at the inner or 
receiving end of which is pro^'idcd as shown a strap of metal i, which 
extends around the bottom and sides thereof and is apcrtured to 
receive and pivotally engage on said shaft B. The discharge end 
of said chute I extends into position to be successively engaged by 
the buckets h^, on the elevator. As the elevator is slowly driven 
by the belt Ir the discharge end of said chute is slowly lifted until 
the chute is about horizontal, at which point it slips off the bucket 
and falls until engaged to be again lifted by the next succeeding 
bucket, tbereby jarring its contents into the buckets of the elevator 
from whence they are of course delivered from the tank. 

As shown, conducting cables B- are secured on said conducting 
shaft B and are electrically connected with the metallic conductor 
c^ in the frame, or if desired may l^e connected immediately with 
the metallic bottom of the tray. 

Extending longitudinally along the top of the tank on one of the 
side walls is a conductor k, and as shoAvn, consisting of a flat strap 
or plate of metal, and hinged on one of said side walls are support- 
ing bars K for the anodes These as siiown m Figs. 85 and 86 are 
bars of wood or any suitable material, each having on the under 
side thereof a bus bar comprising a strap of suitable conducting 
material k^ which rests on the strap k, adjacent the hinge, and at 
the opposite side of the tank rests on a similar conductor k^. Said 
conductors k — ^•' are electrically connected by means of a bus bar 
k^ which extends across the tank and with which one of the leads 
from the source of current is connected. Suitable bolts k'^ extend 
through said bar K and bus bars k^ and rigidly engaged thereto 
at the lower ends thereof transversely the cathode tray are the 
anodes K'-, which may be of any desired number and are conven- 
iently of the metal it is desired to plate upon the articles treated. 
Said supporting bolts &* are progressively longer toward the rear 
end of the tank so that said anodes are all supported at the same 
distance above the tray. 

From the construction described it is obvious that any of said 
supporting bars K with its anode K^ may be swung upwardly out 
of the electrolyte for adjustment or renewal of the anode or to 
reduce the plating surface and control the current density. This, 



188 GALVANIZING AND TINNING 

of course, breaks the circuit through such bus bars without disturb- 
ing the other anodes or interfering with the operation of the ap- 
paratus and affords an important means for regulating the opera- 
tion. To insure a perfect contact when in operation special forms 
of construction are frequently used For this the free end of 
said bar K is provided with a metallic contact piece h° rigidly bolted 
thereto and flanged under the same to engage the bus bar h^ and 
provided with a longitudinally extendnig vertically set web or knife 
h^. This engages wedgingly between contact plates A-^, which are 
integrally connected with a base member h^ bolted or otherwise 
secured to the conductor k-. 

Operation of the Meaker Machine 

The operation is as follows: SuiScient of the electrolyte having 
been placed in the tank A to submerge the tray and the anodes, the 
articles to be plated are delivered into the tray slowly by means of 
a chute f^ and the current is turned on, and the driving shaft ac- 
tuated from any suitable source of power. The rotation of said 
shaft with its cams serves successively to elevate and to drop the 
forward end of the chute /^ upon the cam, the spring, of course, 
pulling the end down with considerable force upon the lower por- 
tion of the cam and jarring the articles into the tray. The cams 
also press the jar bars forwardly until the projection &' passes the 
contact points on the jar bars, whereupon the springs / pull the 
jar bars with the frame and tray supported thereon rearwardly of 
the tank with some violence until stopped abruptly, thus tending to 
jar and deliver or roll the articles within said tray toward the lower 
or discharge end thereof. To facilitate the rolling movement of said 
articles the bottom of said tray is arranged in successive steps or 
ledges, and the metallic contacts whether pins or strips are so dis- 
posed that the articles being treated are at all times in contact Avith 
one or more thereof. The elevator is driven continuously from the 
driving shaft and as the articles plated successively fall into the 
chute I, they are moved rearwardh^ into the Inickets by the move- 
ment of said chute, the rear end of Avhich is raised slowly on one 
elevator bucket to approximately horizontal position when the 
bucket passes from l)eneath the same permitting the end of the chute 
to drop upon the next bucket, and below horizontal, thus jarring 
the articles rearwardly on said chute and into the elevator. 

Of course, overlapping metallic plates D- of copper or other 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 189 

suitable metal either with or without its surface covered or partly 
covered with insulatiu"- material, may l)e emplo3'ed for the bottom 
of the tray and in either case after the cathode surface or surfaces 
have accumulated a considerable coating of the plating metal the 
cathodes may 1)6 removed and fresh plates substituted and the 
plates so coated or partly coated may l)e utilized as anodes until 
the surplus material has plated off. The plates if so used, are of 
course provided with an aperture at each end which is covered hj 
the side rails d of the tray when used as cathodes, Ijut whicli receive 
the supporting rods h* Avhen used as anodes. In this way all the 
plating metal is utilized and inconvenience and loss from the accu- 
mulation of the plating metal upon the cathodes is avoided. 

The anodes in the construction described are capable of being 
removed independently from the electrolyte and any or all of the 
same may be swung ujDwardly, each bus ])ar Ijreaking the circuit for 
its anode, when lifted. This enables the plating surface and current 
density to be at all times perfectly controlled and together with 
the construction of the cathode elements greatly economizes in 
current and material. 

There are also special devices on the market for special classes 
of goods, such as tubes, sheets, wire and wire nettings, etc. 

Hanson and Van Winkle Pipe and Tube Galvanizing 
Machine 

Consideral)le ingenuity has been displayed in adapting mechan- 
ical means to the handling of large quantities of pipe at an ex- 
tremely low cost. The plant for work of this kind consists of the 
dynamo, a series of large circular cypress and iron tanks twelve 
or more feet in depth, Avhicli are arranged in a concrete pit, only 
a few feet of each tank being above the floor level. The pit is 
of sufficient size to contain the number of cleaning and depositing 
tanks necessary and still afford ample room for wiring, connec- 
tions, repairs, etc. 

The work is conveyed on large racks holding from 100 to 150 
lengths of conduit. An electric trolley carries the racks and their 
load from one tank to the next, finally placing the work pickled 
and cleaned in the galvanizing vat, where electrical connection is 
made and the necessary amount of zinc deposited. The work 
never leaves the rack from the time it is first placed in its raw 



190 



GALVANIZING AND TINNING 



mm^^ 




f •• m 


^^^H 




H^H 




^^^B 




^^Hb" 




W^^M 




HBH 




H^H 




H^H 




^^Hl 




HB 




^Hr 




^Hr 




^^M 




IH 




^H 


nliiii 


^Hr~ 




^m 




m 




m 




HJH 




^H 




HH 




asesL. 








__ , :^S^K 




















































































































... .1 - 







ELECTRO-OALVANIZING PLANT AND EQUIPMENT 191 

state on the carrier until it is delivered to the stock room in a 
iinished condition. 

The Potthoff Tube Galvanizing Machine 

Figs. 89, 90 and 91 show a plating device particularly adapted 
for the plating of bars or pipes. The machine is constructed of 
a large tank of considerable length and the widtli governed by the 
length of the goods. Tlie tank is provided with two or more metal- 
lic bars carrying the negative current on wliich the tubes rest and 



Fig. 89. Potthoff Tube Galvanizing Machine 

travel. Above the tank and electrolyte is a special conveyor mounted 
and so constructed keeping the tubes separate and moving same 
slowly through the electrolyte. The tubes are automatically dis- 
charged from this ajjparatus into a hot-water tank. This is a 
patent of Louis Potthoff, of llie United States Electro Galvanizing 
Co. of Brooklyn, N. Y. 

1, in Fig. ,90, represents a suitable tank or receptacle having 
mounted thereon the framework 2, carrying hangers 3, in which 
are shafts 4 4. Mounted on the shafts 4 are sprocket-wheels 5 5, 
around which run chains or belts 6 6. Mounted at intervals on 
the chains are pins 7, which engage the work and move it through 
the solution. The pins 7 may be made of wood or other non- 
conducting material and so shaped as to cause round work, such 
as tubes, to roll when engaged by them. It will be obvious that 
instead of one long chain extending the length of the tank a 



192 



GALVANIZING AND TINNING 



plurality of chains may be used to avoid the objection due to sa|^- 
ging of a long chain, this arrangement also serving to change the 
points of contact between the pins and the work on account of 
their different alinement. The pin is straight-edged on both sides, 
instead of straight on one side and curved on the other, and has 
two separated prongs, so that in cases where the work is short a 
single chain may be used instead of two chains. The pins are 




Fig. 90. Longitudinal Section of Potthoff Tube Machine 




Fig. 91. Transverse Section of Potthoff Tube Machine 



made readily detachable, so that one may l^e substituted for an- 
other. In order to change the points of contact between the pins 
and the work, fixed cams or inclines 8 are provided, against which 
the work will strike and be moved thereby tranversely, so as to 
contact with both the pins and the cathode-terminals at different 
points. 

9 9 represent the anodes, which are composed of the metal to 
be deposited and disposed so that the current may pass from them 
through the solution to the work and thence out through the 
conductor-bars 11, which are covered with insulation, except where 
the work contacts. The anodes may be supported by hooks 10, 



ELECTRO-GALVANIZING PLANT AND EIJUIPMENT 193 

which are connected with supply-mains. These cathode-terminals 
11 form a track or guide which is inclined to the chains 6, so 
that as the work is moved along by the pins the points of con- 
tact with the cathode-terminal continually change, thus permitting 
entire covering of the work with deposited metal. The work is 
fed in at the left and is supported by the pins 7 against the guide- 
bars 11 until it gets to the horizontal portion and is thereafter 
merely moved along by the pins, being supported by the bars. 
Round work is rolled along by the pins as the chain moves; but 
work of angular shape will slide, and in order to insure that all 
the contacts with the bars 11 will not be on one side one or more 
inclines and depressions 13 13 are provided in the cathode, which 
will cause the work to turn over as it is moved along by the pins. 
At the opposite end the work is fed out onto a table or other 
receptacle 1-1. It will be understood that the bars 11 are to be 
connected with negative mains. The discharge end of one bar is 
higher than that of the other, so that the electrolyte will be auto- 
matically discharged from the work before it falls on the table. 

In order to deposit on the interior of tubes, it is necessary to 
pass an anode 20 through the tube 27 without having it contact 
therewith. If an anode be covered with a meshed fabric 29, such 
as burlap, or cocoa-matting, the passage of metal therethrough is 
not retarded and burning, due to contact between the anode and 
the work, prevented. As the inside anode is gradually dissolved, 
the wrapping becomes more loose, thus permitting free movement 
of the anode inside of the wraiDjDing as the work moves along. 

If desired, the current may be conducted to the inside anode 
from the outside anode through the solution without using the 
track 21. As long as the inside anode and the tube are of dif- 
ferent polarities no deposit will be made on the inside anode by 
any positive current which it may receive from any positive con- 
ductor, and this condition will be maintained as long as the voltage 
is not so high as to cause the current to jump across from the 
inside anode 20 to the tube through the wrapping. The thickness 
of the wrapping must therefore be proportioned according to the 
voltage which is to be used. Under some circumstances it will be 
desirable to use a high voltage and thick wrapping without the 
track, and in other cases to use a low voltage and thin Avrapping 
in connection with the track 21, connected with the positive mains. 

It will be obvious that the use of the inside anode is not re- 



,94 GALVANIZING AND TINNING 

stricted to round work, as work of other shapes may be equally 
well galvanized, and it will also be seen that pai'lial tubes — such 
as angles, etc. — may be galvanized on both sides by u^ing appro- 
priately shaped anodes. 

22 is a stiffening-rod, composed, preferably, of wood, which passes 
through the inside anode 20 and prevents its breaking when a 
considerable amount has been dissolved off. For instance, where 
anodes of. zinc are used this stiffening-rod becomes quite essential, 
because of the brittleness of zinc. 

23 represents rotary paddles or propellers which may be driven 
from the shaft 4 by a belt 24 to force the electrolyte to circulate 
through tubular work as it is moved along. 

In galvanizing small pipes it has been found that air sometimes 
becomes trapped in the tube and the meshes of the fabric, espe- 
cially if the tube is carried into the electrolyte horizontally, which 
permits the electrolyte to rush in at both ends simultaneously. By 
feeding one end of the tube in before the other the contained air 
can escape from the end not immersed, and thus prevent the trap- 
ping of air within the tube. This can be accomplished by mak- 
ing the straight backs of the pins higher on one chain than on the 
other, as at 26, so as to incline the tube, and also by setting the 
pins of one chain slightly in advance of the other, the sprockets 
being provided with set-screws for the purpose. It will be seen 
that the tube can be fed in in an inclined position and yet be 
carried through the tank in a straight line, because the tube comes 
in on the back edges of the pins and is fed along by the front 
edges. By setting the pins of one chain in advance of those of 
the other, the electrolyte will be permitted to run out of the tubes 
before they are discharged, or, as before stated, one bar can be 
made higher than the other at each end. 

The King Continuous Wire Cloth Machine 

Continuous methods for handling hoop iron, corset steel, 
cartridge steel and wire netting for window screens have 
been devised which greatly facilitate the turning out of quan- 
tities of work daily at a minimum cost. In equipme;nt of this 
kind the work is placed on large rolls at the beginning end of the 
process (Fig. 92) and is carried through the various pickling, 
cleaning and galvanizing operations continuously to another set 
of rolls at the end of the operation, where the work is reeled up 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 




!-3 



:<)6 



GALVANIZING AND TINNING 



in a finished condition, impulse l^eing imparted to tlie various 
rollers by mechanical means so the work is moved evenly through 
the various tanks. Plants of this character in the United States 
are at present turning out over 100,000,000 sq. ft. of galvanized 
wire cloth each year. 

The reference-character 1, in Figs. 93 and 94, indicates any 
desirable form of supporting frame-work or foundation upon which 
the various apparatus may 1)e arranged. 

Fig. 03. Side Elevation of King's Wire Cloth Machine 




'^ ^^. ^4,'^ 



3i 7"? 50 72 d 

r-v rT-*< 




Fig. 94. Plan of King's Wire Cloth Machine 



The reference-character 3 indicates the standards between which 
are mounted the shafts 3, bearing the reels or drums 4 upon which 
the long lengths of metallic material 5 are carried. The said 
lengths of metallic material 5 are first carried into a cleaning ap- 
paratus, which comprises a metallic tank 6 provided with a bind- 
ing-post 7 to which is attached a wire 8 of an electrical circuit. 
Arranged within said tank 6 is a frame-work 9 which is provided 
with bearings 10, in which are suitaljly mounted rollers 11. The 
said frame-work is supported upon the bottom of the tank 6 by 
means of insulating blocks 12. The said tank G is filled with a 
solution of potash which is kept liot by means of a steam-coil 13, 
or the like, arranged beneath said tank. This potash solution 
cleanses the metallic material as it is passed therethrough, from 



ELECTRO-dALVANIZTNC, PLANT AND KQUIPMENT lf)7 

all grease and foreign material which may cling to the surface 
of the same. The metallic material is drawn from the reels or 
drums 4 and passed under the rollers 11 so as to suhmerge the 
same in the potash solution, and upon emerging from said solution 
of potash, the strips of metallic material pass over a contact-rod 
14 mounted rotatahly hetwecn standards 15. The said contact- 
rod 14 is arranged in the electrical circuit, hy means of a hind- 
ing-post IG, one end of which carries a hrush 17 which rides in 
contact with said contact-rod 14, and the said binding-post being 
connected with an electrical conductor 18, wherel)y the circuit is 
establislied and completed through the tank 6, the potash-solution 
to the strips 5 in contact with the contact rod 14, and through the 
brush 17 and 1)inding-post IG to said conductor 18. Arranged 
adjacent to said tank G is a tank 19 and rotatably arranged in the 
interior thereof is a guide-roller 20. The tank 19 is filled with 
cold water and the metallic material is carried from said contact- 
rod 14, beneath said guide-roller 20, so as to submerge the same 
in the said water, whereby the potash-solution clinging thereto is 
rinsed or washed off, as will be clearly evident. Mounted between 
a pair of standards 21 is a shaft 22 upon which is secured a driv- 
ing or conveying roller 23, over which the metallic material 5 is 
carried after emerging from the water in said tank 19. Arranged 
adjacent to said tank 19 is a tank 24 also provided with an inter- 
nally arranged guide-roller 25, said tank 24 being filled with a 
pickling solution for the purpose of removing any scale or the like, 
which, in cases where the metallic material to be plated has been 
annealed, may cling to the surface of said metallic material. The 
metallic material is carried from said driving or conveying roller 
23 beneath the said guide-roller 25, so as to submerge the same in 
the said pickling solution. 

Mounted between a pair of standards 2G is a shaft 27 upon 
which is secured a driving or conveying roller 28, over which the 
metallic material 5 is carried after emerging from the said pickling 
solution. Arranged adjacent to said tank 24 is a tank 29 which is 
provided with an internally arranged guide-roller 30, said tank 
29 being filled with cold water, and the metallic material 5 is car- 
ried from said driving or conveying roller 28 beneath said guide- 
roller 30, so as to be submerged in the water, and whereby the 
pickling solution clinging thereto is rinsed or washed off of the 
same. Mounted between a pair of standards 31 is a contact-rod 



1S8 GALVANIZING AND TINNING 

3^, and arranged upon one of said standards 31 is a binding-post 
S3;, t9 which is secured one end of an electrical conductor 34 of an 
electrical circuit. Connected with said binding-post is a brush- 
holder 35 in which is arranged a suitable brush 36, the free end of 
which is adapted to be maintained in electrical contact with said 
contact-rod 32. The strips of metallic material 5 upon emerging 
from said cold water tank 29 pass over said contact-rod 32 and are 
thus brought in electrical contact therewith. Arranged adjacent to 
said tank 29 is another tank 37 which is provided with an inter- 
nally arranged guide-roller 38. This tank 37 is filled with a 
solution of copper or Otlier salts so as to provide a copper or other 
suitable bath, and the metallic material 5 is carried from said 
contact-rod 32 beneath said guide-roller 38, so as to submerge the 
same in the said bath. Secured upon the upper edges of the sides 
of said tank 37 are contact-rods 39 which are provided with bind- 
ing-posts 40, a connecting conductor 41 being arranged between 
said binding-posts 40. One of said conductors is connected with 
an electrical conductor ^12 of an electrical circuit. Suspended from 
said contact-rods 39, by means of suitable hangers, as 43, are a 
plurality of anodes 44, so arranged that one group is placed 
adjacent to the upper surfaces of said strips of metallic-material 5, 
and the other group is arranged adjacent to the under surfaces of 
said strips of metallic material 5. IMounted between a pair of 
standards 45 is a shaft 46 upon which is secured a driving or con- 
veying roller 47, over which the said strips of metallic material 5 
are carried after emerging from the said copper-bath ; and, ad- 
jacent to said tank 37 is another tank 48 which is provided with 
an internally arranged guide-roller 49, This tank 48 is filled 
with cold water and the strips of metallic material 5 are carried 
from said driving or conveying roller 47 beneath said guide-roller 
49 so as to be submerged in the said water, whereby any portion 
of the solution still clinging thereto may be rinsed or washed 
off. Mounted between a pair of standards 50 is a shaft 51 upon 
which is secured a driving or conveying roller 52, over which 
the said strips of metallic material 5 are carried after emerg- 
ing from the cold water tank 48, and adjacent to said cold 
water tank 48 is a long trough-like plating-tank 53, adapted to 
be filled with any desirable electroplating solution. This tank 
53 is provided at each end with internally arranged guide-rollers 
54, and suitably disposed within said plating-tank 53, between 



ELECTRO-CALVANIZTNG PLANT AND I^IQUTPMENT 199 

the paid guide- rollorrt 51 and on a slightly lower plane than said 
guide-rollers 5-1-, are a pkirality of supporting or carrying rollers 
55. Mounted between a pair of standards 56 is a contact-rod 57. 
Secured to the upper edge of one side of said tank 53 is a sup- 
porting bracket 58, in the free end of which is arranged a binding- 
post 59, to which is secured one end of an electrical conductor 60 
of an electrical circuit. Connected with said binding-post 59 is 
a brush-holder Gl in whicli is arranged a brush 62, the free end 
of which is adapted to be maintained in electrical contact with 
said contact-rod 57. 

Secured upon one end of said plating- tank 53 are a pair of 
standards 63 in each of which are arranged a pair of sliding 
Journal-boxes 6-1. Journaled in said l)oxes 6-1: are shafts 67, and 
suitably mounted or secured upon said shafts are resilient rollers 
66. Secured to the outer ends of said shafts 67 are gears 65 
which are in mesh with each other and are adapted to drive 
the said rollers in opposite directions. One of said shafts 67 
is provided upon one end with a driving wheel 68 of large diam- 
eter, said driving-wheel 68 being connected by means of a belt 
69, or the like, with a small pulley 70 on a main power shaft 71. 
The said strips of metallic material 5 are carried from said 
iriving or conveying roller 52, beneath one of said guide-rollers 
5-J-. and then extend longitudinally through said plating-tank 53, 
being supported by said supporting or carrying rollers 55 and 
submerged in said electroplating solution, said metallic material 
then extending beneath the other of said guide-rollers 54, at the 
opposite end of said tank 53, emerging from the said electro- 
plating fluid or solution and then passing over said contact-rod 57, 
being in electrical contact therewith, and thence through or be- 
tween the said resilient rollers 66. Secured upon the upper edge- 
surfaces of the sides of said plating-tank 53 are contact-rods 72, 
provided with binding-posts 73, a connecting conductor 7-J: being 
secured to and joining in electrical circuit both of said contact- 
rods 72, one of said binding-posts being connected with an elec- 
trical conductor 75 of an electrical circuit. Suspended from said 
contact-rods 72, by means of hangers 76, are a plurality of anodes 
77, Avhich are arranged so as to be grouped between the said 
!]'uide-rollers 5-t and each of the said supporting or carrying rol- 
lers 55. The said anodes 77 are further arranged in sucli ^. 
manner so that some of the same extend laterally across s»:d 



200 GALVANIZING AND TINNING 

plating-tank 53, adjacent to the upper surfaces of said strips 
of metallic material 5, and other anodes extending laterally across 
said tank, adjacent to the under surfaces of said strips of metallic 
material 5. Arranged adjacent to said plating-tank 53 is a metal- 
lic-tank 78, which is provided with frame-members 79 between 
which are mounted an internal guide-roller 80 and an outer guide- 
roller 81. This tank 78 is adapted to be filled with hot water, 
which is kept hot by means of a steam-coil 82, or any other de- 
sirable heating unit, said coil l)eing arranged beneath the bottom 
of said tank 78. The strips of metallic material pass from said 
resilient rollers 66, beneath tlie said internally arranged guide- 
roller 80, so as to submerge tlie said strips of metallic material 
5 therein, for the purpose of thoroughly cleansing and washing ofE 
of the same any of the electroplating solution still clinging 
thereto, the said strips 5 then being carried over said outer guide- 
roller 81, and thence through the hood 83 of a drying apparatus, 
said drying apparatus being arranged adjacent to the end of said 
metallic tank 78. This drying apparatus comprises a box-like 
compartment 84, supported upon a frame-work or legs 85, and 
arranged therein is a steam-coil 86, or any other desirable heat- 
ing unit. Connected with the compartment 84 and arranged above 
said steam-coil 86 is a perforated plate 87, over which is ar- 
ranged the said hood 83, tho same Ijeing provided with openings 
88 at each end for the entrance and exit of said strips 5, the 
said hood 83 forming a drying chamber 89. 

Mounted between a pair of standards 90, which are located 
adjacent to the drying apparatus, is a shaft 91 upon which are 
secured suitable receiving reels or drums 93^ upon which the said 
strips of metallic material 5 are rolled or wound after passing 
through said drying apparatus. Secured upon one end of said 
shaft is a ratchet-wheel 93, and pivotally arranged upon said 
shaft, adjacent to said ratchet-wheel 93, is a vibrator-arm or lever 
94, the free end of which is provided with a stud to which is 
pivotally connected a pawl 95 which is adapted to engage with 
the teeth of said ratchet-wheel 93. The means for operating said 
vibrator-rod or lever 94 and the pawl 95, to turn or drive the 
said ratchet-wheel 93, comprises a crank-shaft 96, one end of 
which is pivotally connected w^ith said vibrator-rod or lever 94, 
and the other end of which is connected eccentrically with the 
?ide or plane-surface of a pulley 97 secured to a main power- 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 201 

f-naft 98. Tlie reciprocating action of said crank-shaft 9(), 1)^ 
means of said vil)rator-rod or lever 91 and its pawl 95 tims im- 
parts to said ratchet-wheel 93 and tlie shaft 91 a rotary rnoiioji 
as will be clearly evident. This motion is slow, but very positive, 
and assures the drawing of the said metallic strips 5 tlirou;^!! 
the various devices of the apparatus heremabove described, and 
it is finally reeled or rolled in its finished condition upon said 
reels or drums 92. To further aid the drawing or passage o^ 
said strips of metallic material through the said various devices 
of the apparatus, the said shafts 22, 27, 46 and 51, upon which 
are mounted or secured the said driving or conveying rollers 23, 
28, 47 and 52, as well as the various revolving contact-rods 14, 32 
and 57, are all provided with pulleys 99, and are operatively con- 
nected with a pulley 100 secured upon one of said shafts (55, so 
as to pass the driving power from one to the other of said shafts 
and contact-rods 57, 51, 46, 32, 27, 22 and 14, by means of l^elt- 
connections 101, thereby reducing the friction and aiding mate- 
rially in passing the said metallic-strips 5 through the various 
devices of the whole apparatus. 

From the foregoing descrijjtion of the novel plant for electro- 
plating extraordinarily long lengths of metallic material, it will be 
readily seen that such material is easily manipulated for the pur- 
pose of carrying out the various steps of a perfect electroplating 
process, regardless of the length of the material to be plated. 
The material is passed through the various devices and tanks 
of the apparatus, such as the potash-tank, the picklmg-tank, the 
copper-bath tank, and their intermediate cleansing tanks, con- 
tinuously without the necessity of frequent handling. As one 
portion of material is treated to one step of the process, it passes 
on to the next device, there to be further treated, and another por- 
tion follows, in sequence, until the plating-tank is reached, where 
the metal is deposited on said material in carrying out the actual 
plating step, and then the finished portion is drawn through the 
resilient rolls 66 which squeeze off the solution from the finished 
or plated surface. The further cleansing of said finished or plated 
surface is accomplished in the hot-water tank, and thence the 
material passes to the drying apparatus and is finally reeled upon 
the receiving reels or drums in its finished or plated state. The 
»iiovement of said metallic material through the various apparatus, 
wiiile it is continuous is nevertheless very slow, so that sufficient 



202 



GALVANIZING AND TINNING 



time is allowed to permit of the completion of each preparatory 
step, as well as of the main plating-step of the electro-plating 
process, and each portion of said metallic material is evenly and 
perfectly treated to the final completion of the said process. 

The Root Wire Cloth Machine 

Illustration 95 shows an apparatus for electro-galvanizing 
wire cloth. As clearly shown in the illustration, a plating tank 
is provided with metallic rollers ahove the electrolyte and with 




Fig. 95. Perspective View of Root Wire Cloth Machine 



wooden rollers below the electrolyte and resting at the bottom of 
the tank. Between each pair of rollers a set of anodes is adjusted. 
By this construction a large amount of cathode surface is exposed 
to the anode surface in a narrow space. This device is a patent 
of Francis J. Root, of the New York Wire Cloth Company, New 
York, N. Y. To make the process of electro-galvanizing wire cloth 
and similar articles, like wire, band iron and sheets a continuous 
one, similar tanks have to be employed, for pickling, cleaning, hot 
water, drying and enameling. One row of goods is always con- 
nected onto the next one. 

The tank 1 is made of wood and is water-tight to hold any 
suitable bath or solution which may be desired during the plat- 
ing process. Within the lower portion of the tank and also above 
the tank are rollers 3 and 4, which extend transversely thereof. 
The material moved along by suitable pulling or propelling means, 



ELECTRO-GALVANIZING PLANT AND EQUIPMENT 203 

enters the apparatus, passes over a roller in the upper set, then 
down into die bath under a roller of the lower set, out of the 
bath over another roller of the upper set, and so on in vertical 
folds or loops through the apparatus. It will be observed that 
the rollers are in staggered arrangement so that those in the lower 
set are located below the spaces between adjacent rollers of the 
upper set. Directly below the rollers of the upper set and above 
the rollers of the lower set are the metal anodes 5 for providing 
the plating material. 

The lower rollers 3 are supported within the tank by means of 
bearings G carried on the longitudinal members 7, and the upper 
rollers -i are supported in metal bearings 8 carried on the longi- 
tudinally extending members 9 and 10, which are held in place 
by the uprights 10". Either one or Ijoth of the memljers 9 may 
be made of a metal which will readily conduct electricity and, there- 
fore, can serve as a "bus l^ar'' or common electrical-connecting 
means for the upper rollers or cathodes, all of which are electrically 
connected thereto. This "bus bar" or common electrical-connecting 
means is connected to the negative terminal of an electric circuit, 
the positive end of which is connected to the anodes. 

The anodes 5 are supported in place by and suspended from rods 
11 extending transversely across the upper portion of the tank. 
Each of these rods is provided with a depending meml)er 12 lead- 
ing to another "bus bar" or common electrical-connecting means 13, 
to which the positive terminal of the electrical circuit is connected. 
The anodes are provided with hooks to hold them in place, and 
it is obvious that one which has been used can readily be re- 
placed l)y a new one when desired. The anodes are arranged 
directly over the lower rolls and beneath the upper rolls, and are 
located within the. extremities of the body portion thereof. It is 
apparent that said anodes are between adjacent vertically extend- 
ing portions of the folds or la^^ers of the work as it passes through 
the apparatus, thereby bringing all portions of the two broad sur- 
faces of the work close thereto, thus enabling a uniform deposit of 
the coating substance upon the work to be obtained. 

In coating pieces of work like wire cloth, such as is used for 
ordinary window screening to keep out insects, this apparatus is 
particularly useful. 

It will be observed that the work passes out of the bath each 
time it passes over an upper roller and this aids in breaking any 



204 GALVANIZING AND TINNING 

bubbles of gas which may have been formed upon the work and 
also permits gas accumulation to pass off or dissipate into the 
atmosphere. 

As the rollers in the upper set are all connected to an end of 
the electric circuity, the work passing thereover will also be re- 
charged prior to being reintroduced into the bath. 

With the upper rollers or guiding means located above the bath 
it will be observed that the work can be readily inspected at all 
stages in its passage through the apparatus, thereby permitting the 
apparatus to be operated and the process to be effected in the 
most advantageous manner. 

All of the rollers as shown are provided with flanges to retain 
the work in place thereupon. The work could, however, be re- 
tained in place by other means if desired. The rollers serve for 
guiding the work through the apparatus and also for providing 
means to conduct the electricity to the work at several points along 
its path through the apparatus. When driven they also serve as 
means for propelling the work. 

Schulte Wire Galvanizing Machine 

Figs. 96 and 97 show an apparatus for similar purposes, 
and is so constructed to allow the goods to pass between hori- 
zontal anodes on a skeleton framework through the electrolyte. 
Wires, band iron, etc., are from the start fastened with a long, 
flat clamp and arranged horizontally, and through the traveling 
cables or skeleton framework carried through the electrolyte. After 
this through hot water and finally wound up on spools. This 
machine can also be used for electro-galvanizing sheets by a con- 
tinuous method, also small work in bulk quantities when placed in 
a perforated basket and the basket set on the skeleton framework 
'vhich travels through the electrolyte. This apparatus is patented 
by Louis Schulte of Chicago. 

In the tank A, filled with the electrolyte B, is arranged an 
anode formed of the spaced anode-plates C C^, between which 
jDasses the movable cathode-carrier D in electrical contact with 
contact members D\ removably secured by scrcAvs D- to the tank 
A at or near the ends thereof, as plainly indicated in the draw- 
ings. The anode-plates C C^ are connected with the positive pole 
of a source of electrical energy — such as a battery, dynamo, or the 
like — and the contact members D^ for the cathode-carrier are con- 



ELECTRO GALVANIZING PLANT AND EQUIPMENT 



205 



nected with the negative pole of the said source of electrical energy. 
The movable cathode-carrier D is in the form of an endless skele- 
ton frame for supporting the articles and for carrying the same 
through the electrolyte B between the anode-plates C and C\ 

The movable cathode-carrier D, as shown in the drawings, is 
preferably formed of a number of insulated endless cables D^, con- 
nected with each other by insulated transverse bars or rods D*, 

Fig. 96. Side Elevation of Schulte Wire Galvanizing Machine 





Fig. 97. Plan of Sciiulte Wiue Galvanizing Machine 

spaced suitable distances apart and each j^rovided Avith contact- 
points D^, having their terminals exposed through the insulating 
material. Each contact member D^ for the cathode-carrier D 
consists of a frame D'^, fastened in position on the sides of the 
tank by the screws D-, and the said frame D''' is j^rovided with 
an inclined support D", carrying springs U", pressing the under 
side of contact-plates D", so as to hold the latter in firm contact 
at their upper faces with the contact-points D'^, previously men- 
tioned, and arranged on the cross-bars D* of the skeleton frame. 

The insulated cables D^ pass around rollers E and E^, journaled 
in the sides of the tank A at or near the ends thereof, and on the 
shaft E- of the roller E^ is secured a pulley E'^, connected by a 
belt E* with other machinery for rotating the shaft E- and the 
roller E^ to cause the skeleton frame forming the movable cathode- 



206 GALVANIZING AND TINNING 

carrier D to travel through the eleetrolyte and between the anode- 
plates C and C\ 

The rollers E and E^ are preferably loeated near the top of the 
tank A, and in order to bring the runs of the endless skeleton 
frame in proper relation to the anode-plates C and C^ supple- 
mentary or auxiliary rollers F F are employed, journaled in the 
sides of the tank A and over which passes the upper run of the 
endless skeleton frame and under which passes the lower run of 
the said frame, the said runs Ijeing held in engagement with the 
rollers F F by grooved idlers or pulleys F', journaled in the sides 
of the tank A. Idlers F-, similar to the idlers F', engage the 
outermost insulated cables 1)"- at a point midway between the 
rollers F F to properly support the runs l>etween the rollers F F. 

The speed of the endless traveling skeleton fiame carrying the 
articles is regulated to cause a compl(,'te plating of the articles 
on the entire outer surface during the jjassage of the article 
through the electrolyte in the tank A. 

If it is desired to plate small articles, then the same are pla/ed 
in a metallic perforate tray or liasket IT, set on the contact-points 
D'^' of the upper run of the skeleton frame or fastened thereto, so 
that the articles are passed through the electrolyte B and between 
the anode-plates C and C", the same as tlie articles ab>ove de- 
scribed, and directly fastened to the upper run of the skeleton 
frame. It is understood that in practice the large articles or the 
basket containing the small articles are placed in position on the 
upper run of the skeleton frame at the roller E and taken off the 
skeleton frame at the roller E^ 

By moving the articles to l)e plated through the electrolyte the 
hydrogen is continually removed from the surface of the articles 
to insure the formation of a l)right plating deposit on the articles. 
It will also l)e seen that l)y the arrangement described the electro- 
lyte is kept in motion by the moving cathode to allow of using a 
very high current, thus finishing the plating in a comparatively 
short time. 

Electrical Equipment 

A dynamo driven ])y a revolving belt or motor, directly con- 
nected, will supply the necessary amperes and volts required to 
deposit the zinc metal from the electrolyte onto the cathode (goods 
to be plated) and dissolve at the same time an equivalent amount 



ELECTRO-GALVANIZINU PLANT AND ECiUIPMENT 207 

of zinc from the zijie anodes. A voltmeter and an ammeter, as well 
as a rheostat, are required to control and regulate the volts and 
amperes for the different loads and classes of work. 

The generator supplying the current is usually placed within 40 
or 50 ft. of the galvanizing hath, although this distance may be 
increased provided the conductors are also increased in size. A 
safe ruling for every 30 ft. added double the size of the conductor. 
First, 80 1"; second, 30 2"; third, 30 4"; fourth, 30 8". Great 
ad\ance has been made in the United States in the manufacture 
of dynamos for deposition and it is now possible to procure low- 
voltage generators up to 10,000 amperes capacity. Such generators 
can handle 1.000 sq. ft. of work in a galvanizing bath at one time 
or approximately 16,000 sq. ft. of work in a day of 10 hours. This 
is l)ased on using a current of 10 amperes per sq. ft. and allowing 
a 30-minute (le})osit and the necessary time for filling empty tanks. 
In no other form of electro-deposition has the demand lieen greater 
for generators of low tensions and high ampere capacity than in the 
electro-ga 1 \ a 1 1 i z i ug ind ustr3^ 

Opinions differ as to amount of voltage required. It is agreed 
that low voltage gives softer and tougher deposit, Avhile when 
very heavy deposits are required ^w voltage is alisolutcly necessary. 

Some galvanizers use 2 Aolts for light Avork, while others use 
6 volts on the same class of work. The latter saves time, but does 
]iot give as smooth a coating. 

On big Avork it is necessary to have higher voltage, becaiise of 
size of tank and distance from anode, Avhich increa'ses resistance. 

Copper conductors should be made of solid, flat, round or tulni- 
lar copper of size sufficient to carry required amperage. 1 sq. in. 
of copper will carry 1,000 amperes, and 1 sq. ft. of material sur- 
face exposed in galvanizing solution Avill require from 5 to 20 
amperes ; depending on voltage used and conductivity of solution 
and anodes. 

Anodes 

The anode or positive element from which the metal is taken 
is an im])ortant item in the electro-galvanizing process, its purity 
determining to a great measure the quality of the work and the 
proper maintenance of the solution. A cast anode is to be pre- 
ferred, in shape elliptical, round or flat. In a cast anode the 
structure is more open and crystalline than in the plate form, and 



208 GALVANIZING AND TINNING 

this metal is readily disintegrated under the action of the current. 
The anode surface exjoosed should Ijc one-third greater than the 
cathode surface. 

Cost of Installation 

The much slower rate at which the zinc is deposited electrically 
makes the size of the plant larger than for the dipping process, 
and the first cost is, therefore, greater. It should be noted, how- 
ever, that the cost of one cubic foot of tlie electrolyte bath is but 
a fraction of that of the galvanizing bath. 

The solution tanks are usually made of cypress, 3" or 4" stock 
Avith a lining of a mixture of asphalt and pitch, to which, before 
it is set, a coating of hot white l^each sand is applied, making a 
hard, serviceable lining. Tanks for pickling are usually made of 
wood witli a lead lining and tiie tanks for caustics or electro-clean- 
ing are of iron or steel, arranged with steam coils. 



CHAPTER XXII 

Preparing Work for Electro-Galvanizing 

MATEKIAL to be electro-galvanized is cleaned, preparatory 
to immersion in the electrolyte, in much the same manner 
as it is handled for dipping in the hot ijroccss. A com- 
])i'chensive treatment of these methods is given in Chapters V and 
VI of this book. 

While it has frequently been stated that special attention is 
required and considerably more caution is necessary in cleaning 
materials to be cold galvanized, this idea undoubtedly has orig- 
inated from the fact that material which has not l)een thoroughly 
cleaned can be hot galvanized; while the electrolyte process will 
not act on a surface that has not been entirely freed from foreign 
matter, such as oil, scale, sand, etc. AVhile it is true that the 
hot process of galvanizing will largely coat or bridge over such 
unclean surfaces, material which is treated without being properly 
cleaned will not resist corrosion so effectively as carefully pre- 
pared material, because the impurities set up a corrosive action 
between the basic metal and the zinc coating. In some cases it 
has been found that the zinc coating would not adhere to the 
basic metal and the least shock would loosen it. 

Knowledge of the effect of acids and pickles on various forms 
of iron and steel is necessary in arranging the cleaning and pick- 
ling baths. Cold-rolled and malleable iron are readily treated, 
requiring but mild pickling. Hot-rolled steel is usually covered 
with a hard scale which must be jDickled or otherwise treated. 
Cast iron is perhaps the most difficult to treat successfully in the 
electro-galvanizing bath. The foundry turns out so many kinds 
of castings ; the quality depending upon the mixture ; the char- 
acter of the facing used; the temperature at which tlie metal is 
poured : the burning of the sand into the casting ; the porosity. 
All of these are factors which make it practically impossible to 
treat all iron castings similarly. In some instances dry tumblers 
are used with jacks, the dust exhausted by a blower keeping the 
castings clean; water tumblers are used with other kinds of work. 
If the castings have received the proper attention in the foundry, 

209 



210 GALVANIZING AND TINNING 

tumbling will prepare the work so that only a mild pickle need 
be used. 

Removing Sand from Castings 

It must be remembered that while hydrofluoric acid will remove 
sand and scale, great care is required in its use and the strength 
of the acid should be modified. The solution given below will 
cause the least danger to the work if not left in the pickle too long. 

Hydrofluoric acid, 30 per cent 2 parts 

Sulphuric acid, 66 per cent 1 part 

Water 8 to 10 parts 

A hot pickle of 140 to 160 deg. will work much faster than 
a cold one. It is always best to use the pickle as weak as will 
give the desired results in a limited time. A pickle that will 
not properly treat the castings in two or three hours is a dan- 
gerous one to use. 

During the process of pickling, quantities of magnetic oxide and 
scale become detached and, if allowed to remain in the pickle, to l)e 
further acted upon by the pickle, will form a serious source of loss. 
A form of electromagnet has been devised to remove this oxide 
from the bath. 

Removing Oil or Grease 

If the material to be electro-galvanized is of an oily nature, 
that is, if oil or grease has been used in the process of manu- 
facture, the first operation consists in removing this foreign mat- 
ter by immersion before pickling in a bath, preferably hot, of 
caustic soda or a like solution that will have for its effect the 
dissolving of the oil or grease. The strength of the solution 
and the time required to remove the oil or grease depends some- 
what on the condition of the material. If a hot, caustic-soda .solu- 
tion is used, i to i lb. per gallon will be found to answer gen- 
eral requirements. Material should be allowed to remain in the 
bath for a period of 5 to 20 minutes. It should then be removed 
and rinsed in cold water before being placed in the pickling solu- 
tion, as the caustic soda has a tendency to neutralize the acid. 

Removing Mill Scale 

The removal of mill scale from iron or steel is generally accom- 
plished by pickling the material in a bath of sulphuric acid, muri- 



t»REPARING WORK FOR ELECTRO-GALVANTZING 211 

atic acid (hydrochloric acid) or one of the numerous composi- 
tions for the purpose on the market. The strength of the solu- 
tion used, it will he understood, depends on the thickness of the 
scale to he removed and the time in which such pickling is to he 
done. One method recommended is to place the iron in a solu- 
tion of one part hydrochloric or sulphuric acid to ten parts of 
water for a period varying from ^ hour to 5 hours, this depending 
upon tlie thickness of the scale. 

If a sulphuric-acid Imth is used, a -i-per-cent.-by-weight solution 
of commercial acid will be found to answer general requirements. 
It should be used hot, although a cold solution will answer equally 
well if the time for pickling is sufficient. 

On some classes of work, like chain grips for tires, it is neces- 
sary to remove scale, etc., by first hanging in hot caustic soda to 
remove oil and, after rinsing, to pass quickly through a dip of -iO deg. 
nitric acid, rinse again and dip work in a 10-per-cent. muriatic-acid 
solution. After being rinsed again the work is ready for the gal- 
vanizing bath and will readily cover in the deepest recesses. 

Scratch-Brushing 

When a heav}^ pickle is used, or the work is left too long in 
the acid, the surface of the work shows a residue which must be 
removed before the work is placed in the electro-galvanizing bath. 
This means hand work or scrubbing, which adds largely to the cost 
of preparing the work. 

Heavy pieces of material or of a large surface, such as plates, 
should also be scratch-brushed after pickling, in order to remove 
the scum or residue and obtain a thoroughly clean surface. In 
many instances this can also be accomplished easily and satis- 
factorily by placing the material in an electro-cleaning solution 
made up for the purpose in place of scratch -brushing. This solu- 
tion is usually made from a mild caustic (about 5 per cent, free 
caustic) solution 6 deg. B. 

Copper Flashing 

The use of a copper cyanide strike as a preliminary to the deposit 
of zinc has been largely advocated. Some discussion has arisen as 
to the value of the copper as a resistant to corrosion. It has been 
claimed that as zinc is electropositive to both copper and iron, 
it affords protection to each metal. The oxidizing effect of the 



212 GALVANIZING AND TINNING 

atmosphere will in time affect the zinc coating and change it to 
a zinc oxide. Whenever galvanic or electrochemical action is set 
up l)y the contact of iron and zinc and zinc in the presence of 
moisture, it is the zinc that is attacked and not the iron. It is 
claimed by some that there is no galvanic action per se in iron 
coated with zinc and during disintegration the zinc affords pro- 
tection to the intermediate coating of copper, which, in turn, pro- 
tects the basic metal. Others claim that the use of a copper flash 
is 1)ad practice because copper is electro negative to both iron and 
zinc and will, therefore, lead to more rapid destruction of both 
these metals when it is brought in contact with them in the pres- 
ence of tlie corroding medium. It further adds consideral)le to 
the cost. 

A dip copper has been used with some success previous to gal- 
vanizing and is made as follows: 

Water 1 aal. 

Sulphuric acid 1 oz. 

Sulphate of copper 1 oz. 

The work, after being thoroughly cleaned, is immersed for a 
few seconds in this dip and rinsed quickly. 

When the copper cyanide bath is used, the action is similar to that 
of an electrocleaner. Gas is released from tho surface of the work 
by the action of the current and this has a tendency to throw 
off the carbon residue which has remained on the work, and in 
its 23lace on the iron there is deposited a thin film of copper 
which the zinc readily covers. When the copper begins to show red, 
then you know the work is clean. 

Small material, such as bolts, nuts, washers, rivets, etc., is 
handled in practically the same manner, except that no scrubbing 
of the material is required after leaving the pickling bath, the 
same results being accomplished by tumbling it in revolving 
barrels. 

Castings, according to size, are handled in a like manner, ex- 
cept that cold hydrofluoric acid is used for pickling. In some 
instances slight heating has been found to be an advantage, and 
a bath of hydrofluoric acid of 2 per cent, in weight answers gen- 
eral requirements. Sometimes it is scarcely possible to remove 
the scale from steel without the work remaining so long in the 



tkEPARTNG WORK FOR ELECTRO (lyU.V AN IZ1N(! 2i;i 

jiickle tliat tlie softer or more porous parts oi' the iiiclal will he 
over-pick led. 

Tumbling and Sand Blasting 

The removing of oil, grease, oxide and scale from small articles 
in quantities is done by the means of tumbling tb( ni for sc\ci';il 
hours in cast-iron or heavy wooden tumbling barrels, nniniiig with 
a speed of approximately twenty to forty revolutions ])cr minute. 
The articles are charged into the drums and mixed with sawdust. 
The sawdust will remove and absorb the grease, and the rattling 
and tumbling of all the articles against each other for a continuous 
length of time will remove the scale and oxide and produce at the 
same time a smooth and bright finish to the articles. It is a 
general practice to fill the drum about one-third wMth small articles 
and one-third with sawdust, and this sawdust is discharged at the 
completion of the process by sim])1y loosening the cover of the 
drum a little and the sawdust will escape through the opening 
in the revolution of the drum. After the sawdust is removed 
entirely, a few shovels of new and clean sawdust are placed into 
the drum again, and the process repeated to remove the balance 
of the grease, if any. 

Castings are freed from scale and sand preferably by the use 
of a horizontal sand-blast tumbling barrel. It is considered good 
practice to wet roll stamped steel with grit or emery until clean. 
Wire work can usually be cleaned l:y dry rolling with sawdust to 
absorb the oil, then rolling with leather chips until bright and 
clean. The work is then strung on wires or racks and hung in 
lire electro-cleaner for a short time. 

The use of sand blast is recommended where the nature of the 
material and quantity make the operation practicable. Its use elim- 
inates the necessity of the regular pickling process, although some- 
times moderate subsequent treatment is necessary before the mate- 
rial is placed in the galvanizing solution. This process is also 
extensively used for cleaning conduit pipe previous to electro- 
galvanizing. 

Oils and greases should be removed previous to being sand 
blasted, to permit the sand or crushed steel employed to be used 
again. 

Schulte Grinding and Scouring Machine 

The object of the machine illustrated in detail in Fig. 98 
ij to provide a new and improved machine for grinding. 



214 



GALVANIZING AND TINNING 



scouring, scratch-brushing, bufSng, and sand-buffing sheet metal, 
band-iron, wire, and like metal articles and arranged to simul- 
taneou;?ly treat both faces of the article in a comparatively short 
time without requiring skilled labor. 




Fig. !)S. Front Side Elevation of Schulte Grinding and Scouring 

Machine 



Suitable grinding material — such as water, sand, pumice-stone, 
and the like — is fed onto the top and Ijottom of the article to be 
treated immediately previous to the article passing between the 
rollers B and B\ and for this purpose a number of nozzles N and 
are employed, connected with the lower end of a tank N^, sup- 
ported on the top of the frame A and containing the grinding 
material referred to. Now as the article moves forward between 
the rollers B and B^ the grinding material discharged onto both 
faces of the article is carried along l)y the latter, and consequently 
the rotating and transversely shifting rollers B and B^ grind, rub, 
and scour both surfaces of the article. In order to keep the mate- 
rial in tlie tank N^ properly mixed, a stir-up and transversely ex- 
tending screw N- is arranged in the l3ottom of the said tank, and 
on the outer end of the shaft N^ of the said screw is secured a 
pulley N^, connected by a belt N'^' with a pulley N'^, secured to 
the shaft D^ for tlie upper feed roller D, so that when the latter 
is rotated the screw N- in the tank N^ is rotated to agitate and 
keep the ingredients of the grinding material properly mixed. It 
is understood that instead of the screw N^ other suitable means 
may be employed. 

Water is discharged on the upper and lower faces of the article 
to be treated previous to the article passing between the second 
pair of rollers C and C^, and for this purpose nozzles 0- and 0^ 



PRl'^PARTNG WORK FOR ELECTROaALVANIZING 215 

a-.' pro-ided, comiocii'd with a wai('v-sii])|)ly pipe ()■*, Icadini^; from 
a suitable source of water sup^Dly. Now l)y the article passing 
l)etween the rollers C and C^ while the latter are rotated and 
shifted bodily and water is discharged onto the plate at both faces, 
it is evident that the article receives a final scruljbing, so that 
the article finally passes in a ground and scoured condition to the 
delivery-rollers E and E^ and the transporting-rollers F^ for carry- 
ing the finished article off the machine. 

The grinding material used, as well as the water, drips and 
flows into a trough P, arranged in the lower portion of the main 
frame A below the rollers B^ and C^, and this trough P is con- 
nected with the suction end of a pump Q, having its discharge- 
pipe Q^ leading into the overhead tank N% so that the grinding 
material and water is returned to the said tank N^ to be again 
discharged to the nozzles N onto both faces of the next article 
to be treated, thus allowing reuse of the grinding material. The 
shaft Q- of the pump Q is provided with a pulley Q^, connected 
by a belt Q:* with a pulley Q;"' on the shaft B' of the roller B^ 
so that when the latter is rotated the rotary pump Q is set in 
motion to ^Dump the material from the trough P into the over- 
head tank IST^. 

It is understood that when the machine is in operation both 
faces of the article are ground and scoured by the use of the 
grinding material discharged onto both faces of the article previous 
to its passage bet\veen the rollers B and B'. 

The pairs of rollers B B' and C C are made of wood or other 
suitable material or covered with a fa1)ric, according to the nature 
of the material under treatment and according to the particular 
finish to be given to the article — that is, whether the same is to 
receive a scratch-brushing, Imffing, sand-buffing, or the like. By 
passing the article in an inclined position through the pairs of 
rollers the grinding material and water readily flow back on the 
article and finally into the trough. 

Electro Cleaning 

Cleaning work by a low current of electricit}^ is largely prac- 
ticed in the electro-plating industry. Usually an alkaline solu- 
tion is used, costing but a few cents per gallon. Steel or iron con- 
tainers are used for the bath, which is heated to the boiling point 
by means of steam coils. The tank itself is made the positive by 



216 GALVANIZING AND TINNII^G 

being connected with the positive pole of the generator; the work 
in the bath is attached to the negative pole of the dynamo and an 
e. m. f. of 6-8 volts is used, the work being left under the 
influence of the current for several minutes. Gas is thrown off 
freely from tlie work and the surface is cleaned by the action of 
this gas, particles of oxide and grease heing removed. 



CHAPTER XXII r 

Electro -Galvanizing Solutions and Their Application 

S(,)ME of the earliest experiments in electro galvanizing were 
made by the French scientists, and present users are indebted 
to this source, as well as to German and English authorities, 
for some practical information regarding the action of the various 
salts of zinc. A number of Ijaths have been patented both in this 
country and al^roacl, but the most effective and simplest bath is 
that made from the sulphate of zinc, in combination with alu- 
minum, zinc chloride or some similar salt, and it has been deter- 
mined that a bath showing an acid reaction is to be preferred. 

It is unnecessary that .'solutions be used of a composition of 
poisonous ingredients or those throwing off fumes while in opera- 
tion, nor is it necessary to operate them at more than the usual 
room temperature. Their composition should be such as to give 
the highest electrical conductivity; for the thickness of the zinc 
deposit and the length of time required for the coating depends 
on the conductivity to a large extent. Their nature should be 
such as to decompose and deposit the zinc with a minimum libera- 
tion of hydrogen, or the deposit is likely to be found, on exam- 
ination, to be iDorous and of a granular and spongy nature. Ob- 
servance of these' conditions will result in deposits uniformly 
smooth, homogeneous, flexible with perfect adhesion, and in an 
absolute union between the basic metal and coating. 

The upkeep or maintenance of the solution is equally impor- 
tant, and satisfactory results cannot be oljtained continuously un- 
less the solutions are at all times working at their highest efficiency. 

The cause of unsatisfactory work with the electro-galvanizing 
process is frequently attributed to improper cleaning of the mate- 
rial, but the fault sometimes lies with the electro-galvanizing solu- 
tion or electrolyte. While experience in pickling or preparation of 
surfaces previous to galvanizing affords many little short-cuts which 
will result in the most satisfactory and quickest results, it does 
not require the services of an expert or a man of more than average 
intelligence to master it in a comparatively short time. Atten- 
tion to details and close observance of results under varying con- 

217 



218 GALVANIZING AND TINNING 

ditions will enable any one to master this part of the electro- 
galvanizing process. 

The electrolyte or zinc solution can be made up from sulphate 
of zinc (white vitriol) or from chloride of zinc, or from a com- 
bination of the two. An addition of conducting salts, such as 
sulphate of sodium, sulphate of aluminum, chloride of ammonia, 
etc., can be used to increase the conductivity of zinc solutions. 
There are also a number of organic and inorganic chemicals rec- 
ommended and patented for the purpose of producing a more 
dense and brighter deposit. The majority of these chemicals (of 
which we will speak more fully later on) act as a colloid through 
tlje electric current. The following solution has been worked with 
success in an open still tank. 

Formula 1 

Zinc sulphate 200 lbs. 

Sulphate of sodium (crystals) 20 lbs. 

Sulphate of aluminum 10 lbs. 

Boric acid 3 lbs. 

Water to make 100 gallons. 

An addition of a few pounds of zinc chloride, or instead a pint 
of hydrochloric acid, will improve the solution to some extent; 
also an addition of grape sugar will improve a sulphate of zinc 
solution and produce a smoother and more uniform finish, at 
the same time preventing the formation of spongy deposits. 

The above solution can be successfully used for all kinds of 
articles, including wire, liand iron, sheets and wire cloth, and will 
produce l>y three volts and about twenty amperes per square foot 
a white, smooth deposit in thirty minutes which will stand three 
one-minute copper tests, of which we will speak later on. 

Chloride of zinc solutions can also be used to better advantage 
in open tank work, as well as in mechanical plating machines. A 
good solution is comj)osed of the following: 

Formula 2 

Zinc chloride 100 to 150 lbs. 

Chloride of ammonia 50 to 75 lbs. 

Grape sugar 10 lbs. 

Water to make 100 gallons. 



ELECTRO-GALVANIZING SOLUTIONS 219 

111 the open bath a low e. m. f. is used, al)out 3 volts being 
required with a current of 13 to 15 amperes per square foot of 
work surface, the density of the solution Ijeiiig about 20 deg. 
Baume, although a higher voltage can be used if it is desired to 
shorten the time of deposit. For mechanical apparatus, where the 
revolving container is used, the solution is brought to a density 
of 25 to 30 deg. Baume and 8 to 10 volts are used with a corre- 
sponding increase in current. 

The following zinc solutions have also been used satisfactorily on 
different classes of work and under varying condition. They are 
given here so the user of the book may have a basis on which to 
work in experimenting to find the solutions best suited to his 
apparatus and work: 

Formula 3 

Zinc suljihate -ii lbs. 

Pure crystallized sodium sulphate 8.8 ll)s. 

Chemically pure zinc rliloride 2.2 lljs. 

Crystallized boric acid 1.1 11)S. 

AVater 25 gals. 

Formula -i 

Zinc sulphate 50 lbs. 

Ammonium chloride 3.1 11)S. 

Aluminum sulphate G . 2 lbs. 

Water ._,.... 25 gals. 

Formula 5 
Cold galvanizing solution for castings: 

Zinc sulphate 1^ lbs. 

Ammonium cliloride 3 oz. 

Sulphuric acid 1 oz. 

Water 1 gal. 

Formula 6 
Cold .galvanizing solution for barrel plating : 

Zinc sulphate 2,^ lbs. 

Ammonium chloride 6 oz. 

Sulphuric acid 4 oz. 

Water 1 gal. 



220 GALVANIZING AND TINNING 

Formula 7 
Another for regular work: 

Zinc sulphate 1^. lbs. 

Epsom salts '. 8 oz. 

Boric acid -i oz. 

Ammonium chloride 4: oz. 

Water 1 gal. 

Formula 8 
This solution will gi\e a soft deposit that will stand bending 
and forming: 

Zinc sulphate 2 ll)s. 

Ammonium chloride 2 oz. 

Sulphuric acid ^ oz. 

Water 1 gal. 

Formula 9 

Sulphate of zinc 1| lbs. 

Epsom salts 5 oz. 

Sulphuric acid 1/10 oz. 

Water 1 gal. 

Formula 10 

Zinc sulphate 2 lbs. 

Sodium sulphate 4 oz. 

Zinc chloride 2 oz. 

Boric acid 1 oz. 

AVater 1 gal. 

Dextrine 4 oz. 

Formula 11 

Zinc sulphate 1 lb. 

Ammonium cliloride 4 oz. 

Sodium suljjhate 3 oz. 

Sulphuric acid 2 oz. 

A¥ater 1 gal. 

Formula 12 

Zinc sulphate 2 lbs. 

Aluminum sulphate 2 oz. 

Glycerine ^ oz. 

Dextrine 2 oz. 

Water 1 gal. 



ELECTRO-GALVANIZING SOLUTIONS 221 

Formula 13 

Zinc sulphate 2 lbs. 

Sulphuric acid 1 oz. 

Gum tragacantli 1 oz. 

Water 1 gal. 

Formula l-t 

Sodium citrate (crystals ) 5.5 lbs. 

Zinc chloride 8 . 8 lbs. 

Ammonium chloride G . (5 11 )s. 

Water 25 gals. 

Forniula 15 

Zinc chloride 2 lbs. 

Sal ammoniac 10 oz. 

Common salt 3 oz. 

Tartaric acid 3 oz. 

Water 1 gal. 

Formula 16 

Zinc chloride 1 lb. 

Sodium aluminum chloride 5 oz. 

Common salt 4 oz. 

Grape sugar 5 oz. 

Formula 17 

Zinc sulphate '. , 2 lbs. 

Iron sulphate 2 oz. 

Aluminum sulphate ^ oz. 

Sodium acetate -| oz. 

Formula 18 

Zinc sulphate H lbs. 

Sal ammoniac 1: oz. 

Sulphate of soda 2 oz. 

Sulphuric acid 1 oz. 

Water 1 gal. 

Formula 1!) 

Zinc chloride 2 lbs. 

Sal ammoniac 10 oz. 

Tartaric acid 3 oz. 

Sodium chloride 3 oz. 

Water 1 gal. 



222 GALVANIZING AND TINNING 

Formula 20 

Sul2:)hate of zinc 2 lbs. 

Sulphate of aluminum 4 oz. 

Sal ammoniac 2 oz. 

Sodium sulphate 3 oz. 

Water 1 gal. 

Agents for Improving Solutions 

The following additional agents are used to improve either the 
sulphate or chloride solutions, and will cause them to plate brighter 
and prevent the formation of large crystals. A majority of these 
additional agents are embodied in numerous patented formulas: 

Gelatine, dextrine, glue, alum, powdered licorice, gum traga- 
canth and tannic acid. These are called "colloids," and when 
used as additional agents form colloidal solutions or suspensions. 
They cause the solutions to deposit a smaller crystal, making a 
close-grained, smooth, bright coating. 

Glucose, molasses, l^enzoic acid, alcohol, sugar and pyrogallol 
are strong reducing agents, and when used in from three to five 
per cent, additions produce a smooth deposit with great adherence. 

Applying the Coating 

After the articles have been freed of all oxides and scales, which 
means the completion of the pickling ]3rocess, the goods are then 
suspended on wires, hooks or racks and thoroughly rinsed in run- 
ning water and after this ojDcration without any delay are sus- 
pended in the zinc electrolyte from a rod lietween two zinc anodes. 
The anodes also being suspended on rods opposite to the work- 
ing rod. The working rod is connected with the negative pole 
of the dynamo and the two anode rods are connected to the posi- 
tive pole of the dynamo, marked with "-j-" sign. 

If the tumbling of the smaller goods has been accomplished sat- 
isfactorily, there is no further operation necessary and the articles 
can be transferred from the tumbling machinery directly into the 
mechanical plating device, in which they remain from thirty min- 
utes to one and one-half hours, according to the quantity of goods 
to be plated at one time, also according to the different types of 
machine in use, but chiefly according to thickness of coating 
required. 

There are quite a number of plating machines on the market 



ELECTRO-GALVANIZING SOLUTIONS 223 

to-cla}^ particularly adapted for the plating of small articles in 
large quantities, by the means of revolving barrels, having nega- 
tive connections ; connecting with the goods to be plated and mix- 
ing same thoroughly within the barrel, and thus each and every 
article receives an equal, uniform plating. These mechanical 
platers differ from each other more or less in their construction, 
also in the arrangement of their anodes ; some are used outside 
of the barrel and some within the drum only. These have been 
fully described and their operation explained in Chapter XXI. 

Work witli deep depressions cannot be coated satisfactorily with- 
out using anodes shaped to fit the depressions. Increasing the 
voltage to malce it throw in would not make it cover, but would 
result in the outer points becoming granular or burnt. 

Spongy deposits are caused by a too neutral condition of the 
bath, and this can be rectified by testing the solution Math blue 
litmus paper. This test should show a deep red at once if the 
solution is in proper condition, but there should not be enough 
free acid to blue Congo paper. 

If the bath becomes neutral, a tcn-per-cent. solution of sulphuric 
acid and Avater should l)e added until l)lue litmus paper shows a 
25ro23er reaction. 

Such articles as castings, fittings^ stampings, etc., that have 
recesses and depressions, should have some previous treatment. 

The method of procedure is that the fixed time of electro-gal- 
vanizing be cut in two. A strike or preliminary zinc coating 
is deposited from a specially prepared zinc solution and is of a 
dull gray or matt finish. It is advisable then to finish the mate- 
rial in the regular or finish solution, which will then readily coat 
over the entire surface and leave the treated material of a bright 
silvery appearance. Its Milue can be appreciated from the fact 
that it is productive of a quality of work not possible by any 
other means, reduces the time of coating and results in an out- 
put of more than double that possible with the same size equip- 
ment containing only the ordinary electro-galvanizing solution or 
electrolyte. A zinc coating of 25 to 35 minutes, depending on 
the nature of the material, dej)osited in this manner is ample and 
will be found to answer all requirements. 

It is possilile to make a heavier deposit by electro-galvanizing 
l^rocesses by leaving in the solution for a long period. Cast-iron 
rolls have been electro galvanized with coating heavy enough to 



224 GALVANIZING AND TINNING 

stand turning in lathe. This required about ten hours in the 
regular solutions. 

Cost of Operation 

The cost of labor and power are the main items of expense in 
electro galvanizing. Exact figures as to the cost of power cannot 
be given. A larger firm producing their own steam and electric 
power as a l)y-product, figure the cost per kilowatt hour as less 
than one cent; while a small consumer supplied with electricity 
by a local power and light company has to j)ay from four to eleven 
cents per kilowatt hour, while in comjDarison the cost of fuel 
for a hot galvanizing process does not differ to such an extent. 
The labor cost in electro galvanizing and in hot galvanizing is 
about the same, wliile the zinc wasted in the hot process in the 
form of dross seems to be greater than the zinc wasted 1)y the cold 
process in rinsing the Avork from the solution. After a length 
of time, however, if the possil^lc leakage of tanks and the renewing 
of the solution is taken into consideration, the cost of waste in 
comparing the two processes v/ill average al:)Out the same. 

AVhile more time and chemicals have to be applied for the electric 
process than for a hot process, the hot" process will use a larger 
amount of zinc metal by one dip, and this leads to the main argu- 
ment as to whether cold galvanizing is cheaper and better or 
whether the hot galvanized articles are superior and cheaper than 
the others. 

While the unskilled workman in a hot galvanizing plant cannot 
prevent the giving of the iron articles to be coated a sufficiently 
heavy zinc coating, the skilled workman in an electro-galvanizing 
plant is sometimes forced, through local conditions, to give the cus- 
tomer an inferior galvanized article. Therefore, aside from the 
above facts^, it can be easily determined in any galvanizing plant 
using the two processes that, if an equal amount of metal is 
required on sheets, for example, by the liot process, as well as 
by the cold process, the cost of operating and materials for the 
cold process will exceed that of the hot process. However, small 
work in bulk quantities plated in up-to-date mechanical plating 
machines is less expensive than the hot process. 

Numerous arguments have arisen to set forth tliat a dense and 
bright coherent electro-galvanized deposit does not require so much 
zinc deposit as a zinc coating produced by the hot process. This 
problem is still open for discussion^, but practical natural tests 



ELECTRO-GALVANIZING SOLUTIONS 225 

for a niim))er of years, under the same conditions, have proved that 
the amount of zinc applied to iron will guarantee the length of 
time tlie iron is protected from corrosion. 

For example, large pieces of iron sheets galvanized hy the hot 
process and large pieces of iron sheets galvanized by the cold 
process were nailed on top of a roof and additional pieces nailed 
against the chimney of a factory, and in each instance, where there 
was less zinc on the cold galvanized sheets, the galvanizing broke 
down before the hot galvanized sheets. This refers especially to 
such articles where the electro galvanizing does not enter so easily 
into the deeper parts of profiled articles, and consequently the dif- 
ference between hot and cold galvanizing will be much earlier 
shown. 

That this point has been thoroughly recognized and practiced 
is evidenced by the process of plating employed at the electro- 
galvanizing plant of the Spirella Company, Niagara Falls, N. Y., 
illustrations of which are given in Figs. 56 and 57. The problem of 
supplying corset wires which would effectively resist corrosive at- 
tack, due to atmospheric moisture and perspiration, was a serious 
one. Numerous experiments for several years resulted in the 
following coatings being applied. The wires are placed for 45 
minutes in a copper cyanide bath, 45 minutes in an acid copper solu- 
tion, 20 minutes in a nickel solution and 90 minutes in a gal- 
vanizing solution. This is an exceptional case and is interesting 
as probably representing the limit of practice in plating for pro- 
tection, about five- pounds of metal being deposited for every one 
hundred pounds of corset wire. 

The argument about the special test is also a delicate one. The 
Preece test adopted by the United States Government is the most 
reliable and quickest of all tests, and every electro-galvanizing plant 
should use it, if only for the purpose of determining or controling 
the deposition of zinc from the different solutions every day. 

The saline or salt-water test, by the means of spraying contin- 
uously a 10-per-cent. salt solution for a period of from 14 to 20 
days all over the galvanized articles, is also adopted by some con- 
cerns. Galvanizing which breaks down before 14 days have elapsed 
is rejected as inferior. 

Another test is to hang the galvanized articles in a pure-water 
bath in which a continuous stream of air is flowing. 

There is also the cinder test and sometimes diluted sulphuric 
acid is used to test galvanized articles against quick corrosion. 



226 GALVANIZING AND TINNING 

Test for Thickness of Zinc Coating on Armored Cable Strip 

as Provided by Underwriters' Laboratories, in Effect 

September i, 19 13 

The following test is^ in some degree, a measure of the thickness 
of the zinc coating and should be made on at least two samples 
(about 4 in. long) of the finished product going through at the 
time of each visit. Each sample shall be washed in running water 
and then dipped up and down in a vessel containing either carbon 
tetrachloride or ether and allowed to dry before being put into 
the copper sulphate solution. This solution is a saturated solu- 
tion of C. P. sulphate of copper, using distilled water. 

About 100 cubic centimeters of the solution shall be poured 
into a glass vessel about two inches in diameter. The same sample 
of solution shall be used for all dips of any one sample, but a 
new supply of solution shall be used for each new sample. Solu- 
tion, after use, shall be thrown away and in no case put back into 
the supply bottle. The portion of solution used for each test shall 
be brought to a temperature of approximately 65 deg. Fahrenheit 
before the test is made. This shall be accomplished by setting the 
beaker containing the solution in a larger vessel containing the 
warmer or colder water and stirring the solution with a glass 
thermometer until the proper temperature is obtained. 

The sample prepared, as above, shall be stood on end in the 
solution for one minute. The solution shall not be stirred or 
the sample moved during the immersion. At the end of one 
minute the sample is to be removed from the solution and rinsed 
in running water and then wiped lightly, both inside and out, 
with cheesecloth until dry. Care should be taken to avoid violent 
rubbing of the sample and the contact of the surface with the hand 
or anything else than the white cloth used for drying. The sample 
must be thoroughly dried before each dip. 

Each sample shall be subjected to at least three dips and the 
dips should generally be continued until the entire immersed sur- 
face of the sample is coated with a fixed copper deposit. 

The coating will be considered satisfactory, so far as this test 
is concerned, if the fixed copper deposit (i.e., that which cannot 
be wiped off) does not show before the second dip and also does 
not appear on more than 25 per cent, of the surface tested before 
the third dip and wiping process. 



CHAPTER XXIV 

The Art of Sherardizing 

SHERARDIZING, or dry galvanizing, is a process whereby 
articles of iron and steel are rendered rust proof by applying 
a coating of zinc dust. The coating produced by this process 
is first an alloy with the underlying metal. After this alloying- 
action is completed the outer layer of zinc is deposited, the zinc 
jsenetratiug into every crevice and cavity radically different from 
any other method of zinc coating. Briefly stated, this coating is 
not a pure layer of zinc, but a zinc-iron alloy. 

Dry Galvanizing in Prehistoric Times 

A process practically identical to this was known in prehistoric 
times, although used for another pur]30se. At that time it was 
known that if certain copper tools and vessels were placed in the 
ground in certain localities and kept hot for a time by building 
hres over the place, then, on removal, it was seen that the copper 
had assumed a light yellow color and had become harder and more 
duraljle. They practically secured dry galvanizing, although it was 
not known that another metal was being alloyed with the copper. 
Also, in Greek History, according to Aristotle, the "bleaching of 
copper" was done by the same method. 

The Sherardizing process was discovered by accident. Com- 
mander H. V. Simpson, of the English navy, was detailed to work 
out a method of case hardening armor plate for battleships that 
would not infringe on the Harvey patents which were being used 
by nearly all governments for rendering armor plate shell proof. 
These experiments were being tried out in the laboratory of Sherard 
Cowper-Cowles, of London, a noted English metallurgist. A pack- 
age of zinc dust had been forwarded Mr. Cowper-Cowles to de- 
termine whether it could be used in making an electrolyte for zinc 
plating. In the course of their experiments they placed a piece 
of steel in this zinc dust in a case hardening oven and heated it up 
to see if it would have any hardening effect on metal. When taken 
out it was covered with a silvery coating of zinc and on examining 

227 



228 • GALVANIZING AND TINNING 

under the microscope they found it had penetrated and alloyed 
the zinc witli the body of the metal. 

Theory of Sherardizing 

Sherardizing may be defined as a process of sublimation, occlu- 
sion and adhesion, when considered in connection with the theory 




Fig. 99. Section of Sheeaedized Steel Magnified 100 Times 

of ions. The process of passing directly from the solid to the 
gaseous state and from the gaseous direct to the solid state, in 
both cases stepping over the liquid state, is called sublimation. 

The theory of sublimation and the ^'triple point" in connection 
with sublimation is fully defined and described in many elements 
of physics. It is a very well known fact that solids sublime. This 
is easily shown, for example, in the evaporation of ice when it is 
kept below its melting j^oiut. In the case of most solid substances 
this process is so slow at ordinary temperature that it cannot be 
detected. At ordinary temperature and pressure camphor, arsenic 
and many less familiar substances sublime. Solid carbon dioxide 
will volatilize at — 79 deg. C. at atmospheric pressure without 
passing through the liquid state. Zinc as a solid may change into 
vapor without passing into the liquid state. For an exact definition 
of the physical condition of a body a knowledge of the values of all 
its variable 23i"operties is required. The three most important of 
these are temperature, pressure and volume occupied by unit mass 
of the substance. These are not independent of each other but are 
connected by a definite relation called the equation of state, which^ 



Till'] ART OF SIIKRAlIDIZlNa 



220 



ill the simple state of ])erfect <2:ases, takes the form of the gas law, 
which is the law of Boyle and Charles. 

It is a well known fact that common metals are extremely porous. 
This is visible under a hiah power magnifying glass, as well as 
readily demonstrated by certain j)hysical experiments. Thus, if an 
iron wire be placed in a vacuum tube and then heated to incan- 




FiG. 100. Section of Cold Rolled Sherardized Steel Mag- 
nified 1300 Times. Note Zinc-Iron Alloy 



descence,' as, for instance, by passing a current through the wire, 
the pressure within the tube rises materially and gas is evolved for 
a very considerable time, indicating that iron (and practically all 
other metals) contain large volumes of gases. The condition of 
the metal may be graphically described as resembling a sponge 
soaked with water. 

The two photomicrographs reproduced in Figs. 99 and 100 show 
pieces of Sherardized steel magnified so as to show the zinc and 
iron alloy after Sherardizing. 

How Precipitation of a Vapor on Metal Occurs 

When a porous solid is easily permeated by a gas and condensa- 
tion on the surface of the pores of the solid takes place, it is called 
occlusion. An example of this can be seen in the absorption of 
90 volumes of ammonia in one volume of charcoal. Spongy p.lati- 
num will absorb about 250 times its own volume of oxygen. Pa- 
ladium will absorb about 1000 times its own volume of hydrogen 



230 GALVANIZING AND TINNING 

and will increase one-tenth of its volume. To produce such a 
condensation alone would require a pressure of many thousand 
pounds per square inch. Nearly all metals absorb gases and, being 
heated, will allow them to pass through readily. An example of 
this is the fact that hydrogen will readily pass through heated iron. 

When a gas is in contact with a solid, there are molecular forces 
drawing the particles together, and this produces a surface con- 
densation of gas on the solid. An example of this is the difficulty 
in removing the last traces of air from a vacuum bull) due to the 
adhesion of the air on the surface. Another example is the frost- 
ing of window panes in irregular figures. 

There also appears to be an electrical condition accompanying 
the evolution of gases from a metal inasmuch as the evolved gases 
usually contain a number of free ions. This is particularly the 
case if the temperature of the metal is high at the time the gases 
are given off. Naturally the exposed surface of the metal is the 
only portion which actively takes part in evolving gases, so that 
the larger the area of surface exposed the greater the evolution of 
gas, other conditions l^eing equal. 

A further fact, which is well established, is that the presence 
of free ions has a marked effect in producing a precipitation of a 
vapor or suspended matter in a gas It follows, therefore, that 
if a metal be heated in the presence of a vapor under such condi- 
tions that the gases or vapors contained within the metal are in 
part liberated; then, as the liberated gases or vapors contain some 
free ions, they will cause the precipitation within the pores of the 
metal and on the surface layer of a portion of the external vapor 
in which the metal is heated. 

Now it is a well known fact that all materials have a definite 
vapor tension, dejDcnding mainly on the nature of the material, the 
nature of the surrounding materials, the temperature and the 
pressure. It therefore follows that under all conditions all sub- 
stances are surrounded by a certain amount of their own vapor. 
The vapor can be increased in amount by increasing the tempera- 
ture and decreasing the pressure. 

Methods of Producing Zinc Vapor 

Zinc vapor can be produced in several ways from zinc. If molten 
zinc is boiled in a reducing atmosphere, vapor is given off rapidly 
and if heated iron is brought in contact with this vapor Sherardiz- 



THE ART OF SHERARDIZING 231 

ing would take place. This method, however, is neither convenient 
nor economical because of the waste of zinc. The most practical 
and economical method is to use zinc dust, which is obtained as 
a by-product of a zinc smelter. This dust is practically amor- 
phous and each particle consists of a small inner particle of more 
or less pure zinc surrounded by a thin coating of zinc oxide. 

According to a well known fact, the vapor tension is higher for 
small particles than for large. It is thus desirable that the zinc 
be in a very finely divided condition, for the extent or degree of 
penetration of the zinc vapor in the iron depends upon its vapor 
tension. It is also desirable that there be as little impurity in 
the zinc as possible, for not only the zinc, but also the impurities, 
such as lead, cadmium, etc., will give off vapors, and the combined 
vapor tension of the mixture would generally be less than that for 
pure zinc. 

As said l)efore, the zinc particles are surrounded by a coating 
of zinc oxide. This oxide is very inert compared to metallic zinc 
and has a high melting point. It therefore is ver}^ advantageous in 
the process because it not only keeps the particles of zinc separated, 
but allows the spheres of vapor surrounding them to act independ- 
ently with a high vajDor tension and permits the temperature to 
be raised beyond the melting point of zinc without its becoming 
molten. Therefore, the percentage of inert material in the zinc 
dust pla3's an important part in the process. 

Since the process of Sherardizing is being carried on all over the 
country under different conditions and for different purposes, it is 
impossible to give any specific rules for Sherardizing. The follow- 
ing suggestions, however, can be applied in general to all plants 
using this ]3rocess. 

The process of Sherardizing can be divided into the following 
steps or stages, each of which has a definite relation to the whole : 

1. Inspection. 

2. Equipment. 

3. Zinc dust. 

4. Cleaning or preparing of surface. 

5. Temperature and Time. 

As said before, the articles to be Sherardized cannot be selected 
without increasing their cost, but this does not mean that every- 
thing can be Sherardized. If the article is excessively corroded or 
covered by inburned slag (sometimes found with malleable iron) 



232 GALVANIZING AND TINNING 

to such an extent that ordinary methods of cleaning will not re- 
move it, it will not be advisable to attempt Sherardizing. In this 
case such articles should be removed on inspection. Many people 
were of the opinion when taking up this process that anything 
would Sherardize regardless of the condition of the surface, and 
this is the prime cause of the dissatisfaction at the introduction of 
the process. 

Just as in the electro galvanizing and the hot galvanizing proc- 
esses, so in Sherardizing, the surfaces must be thoroughly cleaned. 
A hot galvanizer or an electroplater would not think of galvanizing 
an article that was not free from scale, rust, grease, dirt or other 
impurities, and it is also important that this is done in Sherard- 
izing, if satisfactory results are desired. 



CHAPTER XXV 

Location and Equipment of the Sherardizing Plant 

WHILE the Sherardizing business can be carried on in 
ahnost any kind of a building, the floors should l^e of 
cenieiit or brick as a safeguard against the excessive heat 
of the Sherardizing cylinders or drums. Outbuildings of one story 
are preferable, as it is entirel}- practicable to combine the pickling 
and cleaning with the Sherardizing. AVhile the space required for 
a complete Sherardizing plajit ^•aries according to the demands and 
volume of work to be handled, a plant of a daily capacity of one 
ton for treating miscellaneous articles, such as Ijolts, screws, nails, 
chain, stampings, etc., can be carried on very comfortably in a floor 
space of GOO square feet. 

Little can be said in regard to equipment unless the articles to 
be Sherardized are determined. If there are bolts, nuts, washers, 
stampings, forgings or articles of malleable cast iron, the equip- 
ment would be very different than in the case where large railroad 
material, structural iron, etc., are treated, or where continuous 
Sherardizing is applicable, as with wire, woven wire cloth, nails, 
sheet metal, chains, etc. 

Fig. 101 is a typical layout of a floor plan showing positions of 
an actual Sherardizing plant. The general equipment of an ordinary 
Sherardizing plant consists of a furnace, drums, transfer trucks, 
R. R. track, cooling frame, pyrometer, dust screening machine, ash 
cans for holding zinc, loading frame, "I" beam, carriage and hoist, 
drum pulling machine, pickling tubs, tumbling barrels and sand 
blasting outfit. 

The old pickling tanks which are now used almost exclusively for 
galvanizing work coiisist of four large wooden tanks set end to end 
and one iron tank. Each taidv has a water and steam inlet and 
a drain pipe. The new pickling tanks are used for Sherardizing 
work and consist of eight small tanks set in a row in groups of 
two. The first tank contains potash, the second hot water, the 
third hydrofluoric acid, the fourth hot water, the fifth sulphuric 
acid, the sixth hot water, the seventh lime water and the eighth 
hot water. Each tank is equipped Avith a steam and water inlet 

233 



234 



GALVANIZING AND TINNING 



and a drain while tlie liot water tanks also have overflow pipes. 
An electric hoist rinining on a Clolmrn track runs over the pi(.'kling 
tanks and is used to lift the ))askets of material from one tank to 
another. A sand tumbler is also used to clean the material to be 
Sherardized. 




I'lO. ]01. Floor Pt.an- of Shekakdizing Pi-ant 

The Sherardizing Furnace or Oven 

There are several different st3des of Sherardizing ovens or fur- 
naces in use,whicli will hold one or more drums, according to the 
capacity required. 

Coke Burning Furnace 

Figs. 102 to 106 show the type of a coke Imrning furnace designed 
by A. F. Schoen of tlie New Haven Sherardizing Go. This furnace 
is especially valuable in suburban districts where no other fuel is 
available. The furnace is built of {)" fire brick walls reinforced 
with steel jalates; has individual damjDer controls so that the 
heat, which passes between two arching bridges, can be directed to 
either the front or the rear of the furnace. It is built on the down 
draft principle, the heat passnig directly over and on top of the 
drams. A baffle plate is dropped about 6" below the inlet and uni- 
formly distributed in the furnace. The surplus heat is then taken 
off underneath the floor and passes out under the furnace diagon- 
ally, making a super-heating furnace. Owing to the fact that the 



LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 235 




I'iG. 102. View of Coke Burning Fuknace of Three-Drum Capacity 




-9'3l"- d 

Fig. 104. Front Elevation of Three-Drum Coke Burning Furnace 



236 



GALVANIZING AND TINNING 




Fig. 103. Anotheu View of Same Furnace, 
Showing Operating Devices 




Fig. 105. Side Elevation of Tiieee-Drum Coke Burning Furnace 



LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 237 



heat strikes the drums on the upper side, it has l^een found that 
the work must rotate more constantly than is necessary in a 
gas and oil hurning furnace. Under these conditions it is 
necessary to have an automatic rotating device. 

■-=1 

r 




Fig. 106. 



Section of Thkee-Duvm Coke Burning Furnace Taken 
Above Firebox 



The details of construction are clearly shown in the elevations 
aud sectional drawings given in Figs. 104, 105 and 106, 

Single Drum Coke Burning Furnace 

Fig. 107 illustrates a single drum coke burning furnace also 
built by Mr. Schoen. It is reinforced on three sides with steel 
plate, with an inner lining of 9 inches of firebrick and single arch. 
A feature of this furnace is that it can be grouted so as to bring 
the door proper in line with floor, which obviates the necessity 
of a transfer car. This also applies to furnace in Fig. 102. The 
grouting can only be done on the ground floor. The details of 
construction and general operation are clearly shown on the floor 
plans and elevations given in Figs. 108, 109 and 110. This fur- 
nace can be lengthened to eight feet long and operated uniformly 
from a three-foot firebox. 



238 



GALVANIZING AND TINNING 



Note the drum turning device through furnace door. This was 
necessary through lack of room in rear of furnace at which point 
all rotating devices are generall}^ attached. 

Controlling Heat of Single Arching Furnace 

Unlike the double arching furnace, which forms a pocket from 
which the flame and heat are uniformly forced into the furnace, 




Fig. 107. Single-Drum Coke Burning Furnace 



in a single arch furnace it comes directly over the inner wall as 
shown in Fig. 109, and the flame therefore has a tendency to go 
to the rear of the furnace even though the exhausts are at the front. 



LOCATION AND EQUIP:\IENT OF RHERARDIZING PLANT 239 

This is overcome l)y tapcriii,i( the outlet or haffling the brick at 
various points. A baffle pUite is attached to the arch directly over 
the drum to brake the flame and direct the heat so it will Ijc uni- 
formly distributed around the drum or receptacle. 

Gas and Oil Burning Furnaces 

Fig, 111 illustrates a small self-containing furnace built of struc- 
tural iron and brick, with the cover attaclicd l>y hinges, lined Avith 




-i>l<- — ,— ^'2!'- 

Fig. 108. Fkont Elevation of Single-Drum Coke Buening Furnace 




Fig. 109. Side Elevation of Single-Drum Coke Burning Furnace 



240 



GALVANIZING AND TINNING 



fire brick and fire clay on the inside for gas or oil burning. 
The material Sherardized in this oven would probably be 
bolts, nuts, washers, small malleable cast-iron articles, small 




Fig. 110. Section of Single-Druji Coke Burning Furnace 




Fig. 111. A Self-Contaimld Gas, ±i ukxaue and Drum 



castings and forgings and all small or medium sized iron or 
steel pieces that would pass through an opening 10 x 3G in. A 
special feature of a furnace of this kind is tliat it can be placed 



LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 241 

anywliere in the factory and operated at very little expense, re- 
quiriiio- no elaborate equipment in luiiidlini>', and is very convenient 
e\on ill tiie factories where lar^e Shcrardi/in^- plants are in opera- 
tion, due to the fact that small sjDecial work, which could not be 




Fig. 112. Gas Burning Furnace Used by New Haven Sherardizing Co. 



run in furnaces where two and three cylinders were operating at 
one time, can be taken care of. 

Fig. 112 illustrates the type of gas burning furnace used. This 
style of furnace is also operating successfully with natural gas, 
producer oil and fuel oil. 

Figs. 113 to 114 are detailed sectional views of gas and oil burn- 
ing furnaces. You will note that the only difference between the 
two furnaces is that the combustion chaml3er for the oil is more 
thoroughly reinforced at the floor lines, the combustion taking 



242 



GALVANIZING AND TINNING 



2)lace between the floor and the upper baffle bricks and coming 
out at the sides. The gas burning is an open flame directly against 
the drums, taking air from underneath the furnace, the air fol- 
lowing along the burners. This applies where no pressure is used. 
In cases where gas is used under pressure then use the same equip- 



Door Hoist 



■7-T~T> — T' 



f^s ,,- Angle Iron for Gas Burning only 



^ 



-^ 



.■4"Tlrons-, 



JL 4"^4"^m_^. 



:' , 4"Tile for Oil 
■ /' Burning only 
I ', Gas 

,;^g Q.-Burners- 



s; 



s: 



2" space befwee i 

■' Baffles 

Brick r^--Peef 

Pier g^ Holes 



T*7= 



l-'^ 



Hi: 



a 



X 



u. 



k-A;. 



-2" Pipe 



-----7'6"'k 7 

Baffle Brick for Oil Burners 



Fig. 113. Section of Furnace Showing Difference in Reinforcing of 
Combustion Chamber foe Gas and Oil 



T 



B 



x_ 



Wall 



or 



■vh- 

II l' 



iS 3^ 



.-- Baffle 
Tile 
\/n3 
Sections 



-AirMix.er 



Gas Cocks 



Fig, 114, Plan of Furnace Showing Arrangement of Combustion 
Chamber for Gas and Oil 



Location and equipment of sherardizing plant ^4S 




244 



GALVANIZING AND TINNING 



ment as for oil, allowing more relief from the combustion chamber 
or a slight baffle which will distribute the fiame uniformly. 

As shown in Fig. 113, an angle iron is to be used for gas burning 
at that point only; for fuel oil, which gives off great heat and back 
jjressure at intake, would quickly warp any metal parts and render 
it useless as a frame support. A tie rod at the floor line well pro- 
tected with bricks is recommended. 

Fig. 115 shows a furnace in the plant of the American Tap 




Fig. 116. 



Two COMPABTMENTS OF THE FUENACE SHOWN IN FiG. 115 READY 

TO Receive the Drums 



Brush Co., of Detroit, Mich., which has a capacity of twenty tons 
per day. The drums are 5' long, 18" in diameter, and the furnace 
is so built with separate chamljers that, if the treatment of longer 
material was required, they would simply have to couple the drums 
together to any desired length. This plant would be a valuable 
I^lant to any one doing jobljing work and having a variety of ma- 
terial to be treated in different lengths. 

Fig. 116 shows two comj)artments of the furnace ready to receive 
an 11% ft- drum. It also shows the method of turning the drums 
and the combustion chamber. 



lOQATION AND EQUIPMENT OF SPIERARDIZING PLANT 245 




Fig. 117. A Fuel Oil Burning Fuknace of Four-Dkum Capacity 




Fig. 118. Type of Oil Burning Furnace 



246 



GALVANIZING AND TINNING 




LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 247 




248 GALVANIZING AND TINNING 

Fig. 117 is a view of the John Finn Metal Co.'s plant, in San 
Francisco. This is a fuel oil burning furnace of four drum ca- 
pacity. The drums are rotated by a reciprocating movement of 
the carriage from one end of the furnace to the other. Consider- 
able space could have been saved in this furnace by installing a 
pivot motion. 

The pivot motion is shown in Fig. 118, which illustrates the type 
of furnace used ]>y the Westinghouse Electric and Mfg. Company 
and the Union Switch and Signal Company. This furnace was 
installed for oil fuel, but there is no reason why it may not be 
used for gas, producer gas or natural gas. All that is necessary is 
to change the inside floor plans to provide the desired combustions. 

Figs. 119 and 120 show the loading and cooling platforms 
of a furnace operated by the National Metal Molding Co., 
of Pittsburg, for treating conduit pipe and conduit fit- 
tings, and has a capacity of about thirty-five tons per day. This 
type of furnace is also recommended for water pipe and tubing. 
The drums'are automatically taken into the furnace on very heavy 
chains and are automatically rotated with a sprocket attached to 
the center of the drum, the chain passing beneath with a continu- 
ous movement and protected from the flame. 



Fig. 121. Series of Electric Heated Sherardizing Machines 

Electrically Heated Furnaces or Drums 

A new departure in the Sherardizing field is the special type 
of electrical heated apparatus designed for the General Electric Co. 
This company coats considerable malleable iron and they are now 



LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 249 




Fig. 122. 24" x 24" x 40" Electric Heated Sherardizing Machine 
IN Operation 




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Fig. 123. Layout foe Wiring of Electric Heated Sherardizing 

Machine 



250 GALVANIZING AND TINNING 

using two sizes of machine; one 10" x 10" x 17" inside dimensions 
and requiring 15 kw. to bring up to the desired temperature and 
5 kw. to hold correct temperature, and a larger one 24" x 3 i" x 40" 
inside dimensions requiring CO kw. to heat up and 15 to hold 
at that temperature. The former is illustrated in Fig. 121 and the 
latter is shown with connections for heating in Fig. 122. 

It will be noted that the machines are rectangular in shape and 
are revolved ])y a driving motor mounted on one of the pedestals 
and geared to the drum through a reduction worm gear. The 
heating elements are placed on each of the four sides and both 
ends of the machine, and the current is supplied to them through 
three collector rings at one end of the machine. 

Wiring Diagram 

The connections are such that the drum can be operated on a 
three-wire 250/125 volt D.C. circuit or a three-phase A.C. circuit. 
The only change necessary for a three-phase A.C. circuit is to 
leave off the wire leading to the bottom middle clip of the T.P. D.T. 
switch. 

The general scheme of inside and outside wiring for the two 
drums may be seen in Fig. 123. This layout is for a 250/125 volt 
D.C. circuit. 

Drums 

The requisite number of drums or containers can be made in 
either cylinder, square or flat, suitable for material to be treated. 
For instance, .-mall articles that can be handled readily with a 
shovel or chain in bundles it is best to treat in a round cylinder, 
averaging from 15" to 20" in diameter and up to 6' long. It is 
not necessary to make these drums out of heavier than i/^" boiler 
plate, as there is no actual wear in the low degree of heat main- 
tained. It has been known that drums in daily use up to eight 
years show practically no wear and are as good as new. 

A square drum is used a great many times for light material, 
and a top opening cover is recommended instead of an opening at 
the ends. This will allow perfect packing, so that when the articles 
are taken out they will not be bent or warped. It is, however, 
recommended that drums not over 20" square be used on such light 
material to insure uniform penetration. In the case of flat stock 
for panel work, etc., a flat drum of not over 16" in depth is 
recommended, as the stock, being flat, will lie very closely and it 



LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 251 

would be impossible to get a i)erfeet, uniform coating if the diameter 
was increased. The length and width make no difference. 

Fig. 12-i illustrates a cylinder drum 15" to 20" in diameter, made 
of Vi" boiler plate, welded. The liange and liead are cast or 
mallealile iron and are machined to make a dust proof fit. There 
is one feature that deserves special attention. It is the use of 
slotted parts instead of holes for fastening on the heads. Ordi- 
narily the bolt will expand with the lieat to such an extent that it 
is impossible to remove the nut, but with the above arrangement 
the bolt can be removed without injury, or where the nut will not 
come off it will loosen sufficiently to work out of the slot. 




Fig. 124. A Cylinder Drum 

Dust Separating Machine 

Fig. 135 gives a sectional view of a dust separating ma- 
chine. This screener, which is known as a cylinder screener, 
is made of structural angle iron, 2i/^" x i/4", and matched 
boards, thoroughly reinforced, and the screen is made of per- 
forated metal. The work is received at one end, the dust 
dropping through into a receiving box and the material com- 
ing through at the other end free from dust. It has been found, 
in a good many instances, that on flat stock or cup-shaped material 
the dust is not all relie\ed at the first screening, in which case a 
conveyer is made of two pieces of 5" x 5" angle iron and a carrying 
belt is placed on the receiving end of the screen and conveyed to 
another screening machine of the same type, which will relieve 
such zinc as has passed through the first screener. A conveyer of 



252 GALVANIZING AND TINNING 

this type is very easily constructed and inexpensive, and saves a 
lot of shoveling and handling. The gear pattern is so arranged 
that it can l^e operated with worm drives. 

Fig. 125 illustrates the style and make of dust separating machine 
used. This screen can be placed anywhere on the floor, no pits or 
conveying device necessary. The machine will hold about three 
thousand pounds of zinc at one screening. 



Fig. 125. Dust Separating Machine 

Mr. tSchoen of the New Haven Sherardizing Co. has spent a 
numVer of years perfecting this machine, and l^elieves that a ma- 
chine of this type should be part of the equipment of every plant, 
for it is inexj)ensive and turns out clean work. An exhaust hood 
should be attached to carry all zinc residue to the reclaiming box. 

Fig. 136 shows this same screener in operation, receiving the work 
from the drum ; also a hood placed in such a position that the light 
zinc dust, which is bound to fly, is taken care of under a slight suc- 
tion. The drum is conveyed by means of an overhead trolley. The 
head is removed from, one end of the drum and the material is 



LOCATION AND IXiUlPMENT OF SHERARDIZING PLANT 2.13 

clumpt'd into the ho])i)er. The screen revolves al)out forty revolu- 
tions i)er minute, the dust droppiiig through into the receiving hox 
below and the material coming out at the other end. A hood is 




Fig. 12G. Dusx .Sckeener in Operation 



placed over the receiving hopper at the end where the material 
comes out ; an exhaust is attached with enough suction to take care 
of whatever dust may escape. This is exhausted into a canvas- 
covered box and saved. 



The Transfer Car 

The transfer car is not of any special make. It is merely used 
for transferring drums from one place to another and can be 
easily built from structural iron with a few cast-iron wheels and 
bearings, thoroughly reinforced. Generally speaking, these are 
specially manufactured to meet the requirements of different plants. 
Fig. 127 shows one type of truck used. The "T"' l)eam is standard, 
generally using the very lightest, as the weight ordinarily carried 
in one of these drums is not over one ton, 



254 



GALVANIZING AND TINNING 



Fig. 127 also shows three drums placed in position and secured by 
a locking- frame, which l<eep3 the drums the right distance apart 
and transforms same into a track. They are standard cylinders 




Fig. 127. Transfer Car and Drums 




Fig. 128. Rolling Drums into Furnace as a Unit 



LOCATION AND EQUIPMENT OF SHERARDIZING PLANT 255 

with gears attaclied to drum lieads. Tlie driving gear coming at 
the rear end inside of the furnace, as shown in Fig. 103, turns all 
three drums uniformly, as they are all interlocked. These can also 
be operated individually without gears, as shown in Fig. 128. 

Note. — The wheels placed loosely on the hub act as a bearing and 
truck. This method is recommended, as it obviates the necessity of 
using heavy structural iron trucks, which mean an additional 
expense for heating of additional iron and also the trouble of keep- 
ing the truck from warping. 

Fig. 128 illustrates furnace receiving drums from the transfer 
car. 

This operation is handled mechanically l)y a pulling device at 
the rear of the furnace; but as extra large bearings are used, one 
man can easily push the drums into the furnace : In case of in- 
dividual rotating or turning the stems as shown are then pushed 
into the hub of the drum, which also holds the drums in position. 
With gear drive they are locked into position with a clutching 
device on the track at the front of the drums. 

Cooling Frames 

Cooling frames need no special specifications. Two pieces of 
railroad track or channel iron, mounted so that they meet the 
transfer truck, are all that is necessary. 

Pyrometers 

Every furnace should be equij^ped with a pyrometer, which is 
placed on the wall in the operating room, a certain distance away 
from tlie furnace, and thoroughly protected in a dust-proof case. 
The leads can be bought any length to go with the instrument, and 
are always standard. Eocording instruments are highly recom- 
mended. Chapter III gives special attention to pyrometers. 



CHAPTER XXVI 

Materials Used in Sherardizing 

CONCEENING the practical side of Sherardizing, the arti- 
cle to be Sherardized must be regarded, first, in respect to 
its ability to absorb zinc vapor, and then the condition 
under which zinc produces vapor at the highest tension. 

The articles to be Sherardized are almost exclusively of iron in 
its different stages and forms, as cast iron, malleable iron, wrought 
iron, cold-rolled steel and steel in all its stages. Many kinds of 
iron articles have to be dealt with in many forms and stages and 
quite naturally they would have different rates of occlusion, due to 
the nature of the structure and form and quality of surface. The 
articles to be Sherardized cannot be selected to any extent and the 
specifications under which the articles are being made cannot be 
changed without affecting their cost. Therefore, the most favor- 
alile condition under which the given article will absorb the most 
zinc vapor must be o])tained. In some cases it will be a selection 
of temperature or pressure; in some cases it will be the treatment 
of the article, as annealing, or annealing under a reducing atmos- 
phere, and in some cases, in the treatment of the surface mechani- 
cally (sand blasting and tumbling), or chemically (pickling). 

In the theoretical discussion, mention was made of the effect of 
temperature as an important factor to both elements of the process. 
In this connection it would be well to note that a critical point 
exists for the articles Sherardized, for not all articles to be Sher- 
ardized could be heated to tlie same degree without changing their 
physical properties. From this we see that the definite temperature 
for each special condition must be determined, which is best for 
both the zinc dust and the treated article. 

The material used in the process of Sherardizing is commercial 
zinc dust, commonly called blue powder, of which, at this time, 
about 90% is imported and which, as an average, runs from 75% 
to 90% metallic zinc. Grasselli zinc is also used, but mostly in 
keeping up the strength after the zinc has been reduced to a low 
percentage. This is made from gromid spelter and must be run 

256 



MATERIALS USED IN SHERARDIZING 257 

at a mucli lower degree of lieat than the l:»lue powder. Zinc dross 
is also used, hut not very successfully, as it will not alloy itself with 
the work as thoroughly as the finely powdered zinc, although when 
the two are combined in equal parts they show very good results. 

Dust from the Zinc Smelter 

There are two kinds of zinc dust on the market for commercial 
purposes, Grasselli and common blue dust. Blue dust is a by- 
product of a zinc smelter and is mostly imported from Belgium and 
Germany. Grasselli dust is manufactured in this country from 
metallic zinc. The zinc dust should be kept dry, and if new zinc 
dust is used it should be dried out for several hours in the Sher- 
ardizing drums at 100 deg. C, slowly rising up to 250 deg. C. 

The blue dust can be used with a lower metallic percentage. Less 
time is required for the run in the oven (5 to 6 hours). The quality 
of coating is better, as it is more uniform and solidified. Black 
spots are practically eliminated. There is no danger of fusion, 
bailing, balling, and caking, irrespective of the various high tem- 
peratures. High temperatures can be used. 

The drums, however, cannot be opened when using blue dust 
until a relatively low temperature has been reached, due to the 
very quick oxidation and danger of ignition. A longer period is 
therefore required for cooling. There are difficulties of handling 
this dust without a proper ventilating system and adhesion of 
loose dust to threaded and knurled surfaces occurs. 

Freeing Dust from Iron 

The dust is run through a magnetic separator at least once 
every four weeks to take out superfluous small particles of iron 
which are liable to become lodged between the jaws of cotter pins, 
etc., and thus cause trouble in assembly. By cleaning the dust this 
way the mechanical incorporation of large percentages of iron dust 
in the coating is also prevented. It is recommended that the 
Aveekly analysis of working dust show the iron content. 

The Use of Manufactured Zinc Dust 

A brighter metallic coating is obtained than with the blue dust. 
Less time is required for cooling and less danger is encountered in 
opening the drums when hot. 

A higher metallic percentage is, however, necessary and a longer 



258 GALVANIZING AND TINNING 

time is required for the run in the oven. There is also danger of 
fusion of zinc due to slight overrunning of temperature. 

Method No. i for Determining Metallic Zinc in Zinc Dust 

Into a 400 c.c. Erlenmeyer flask weigh 10 grams of zinc dust, 
to be investigated. Measure 10 c.c. of metallic mercury into same, 
add 100 c.c. of boiling hot water, and run into same from a burette 
the excess of standard normal HCl, the amount added depending 
entirely on the oxide contents of the dust under investigation. 
(From 30 to 50 c.c. usually suffices unless the dust is unusually 
high in oxide.) After the excess of acid is added, as shown by 
methyl orange, insert a stopper and shake for several minutes until 
the metal is completely alloyed, and the oxide is dissolved, with the 
exception of a small amount of coal dust and insolul)le matter 
which usually accompanies such products After the solution is 
effected, decant off the liquor from the mercury alloy, wash the 
alloy by decantation in the flask, and titrate the excessive acid 
with standard normal soda solution until same is exactly neutral, 
as shown by change of indicator, as well as by faint precipitation 
of zinc in solution; calculate the percentage of oxygen (1 c.c. of 
normal HCl being equal to .008 oxygen) from which the zinc 
oxide can readily be calculated. 

1 c.c. N.HCl =: 0.0203 gram zinc oxide 
Per cent, of metallic zinc r- 100% less % of zinc oxide 

Method No. 2 for Determining Metallic Zinc in Zinc Dust 

Weigh out exactly 0.2939 g. of dust and introduce same in a 
200 c.c. Erlenmeyer flask. Add a piece of Pt. foil as a catalyte. 
Add 30 c.c. water. Put 10 c.c. cone. H^SO^ into a small bottle 
and lower same into flask without spilling. 

Connect up flask to gas burette. Invert flask enough to mix acid 
with water. After standing for 3 hours, read ofl: on burette number 
of c.c. hydrogen generated by action of acid on zinc. Make correc- 
tion for temperature. Number of c.c. gives per cent, metallic zinc. 

If, after having determined the proper conditions to get the 
correct results in Sherardizing, these conditions are held to during 
the operation, the results will be constant. If these conditions are 
allowed to vary be^^ond reasonable limits, then the product will 
vary, and the Sherardizing will be irregular. 

It is my belief that these impurities have little or nothing to do 



MATERIALS USED IN SHERARDIZING 259 

witli the |)r()|)ortics of zinc dust and that the reason should be 
sought ft)r it ill its mode of production. 

Method No. 3 for Determining Metallic Zinc in Zinc Dust 

To prepare permanganate of potash titrating solution (it is not 
a clarifying solution) weigh out 5 g. of pure fresh permanganate of 
potash crystals — :\veigh accurately — dissolve in 500 c.c. of pure dis- 
tilled water at 60 deg. F. or thereabouts, i.e., upset the crystals into 
a dry glass-stoppered flask and then fill up with water to the 500 
c.c. mark. Do not put the water in and then the crystals after- 
wards, which would make the solution one or two per cent, too 
weak. Place glass stopper in position, shake well till dissolved and 
then store in a dark cupboard. It will keep for about a fortnight 
or so, but for competitive or buying or selling samples, where ex- 
treme accuracy is wanted, always make up a fresh solution. 

Weigh out from a previously carefully selected sample of zinc 
dust, 1 g., weighing same to a hair; suspend in about 2 in. of 
distilled water in a glass beaker 3" in diameter — beaker large 
enough to hold a pint. Add to this 12 to 20 g. (according to pre- 
sumed metallic value of dust) of pure ferric sulphate, and stir it 
and grind it with a glass rod for 20 min. off and on till all the 
zinc dust and all the ferric sulphate is dissolved with the exception 
of a few possible impurities at the bottom. Test these, however, by 
grinding them with the glass stirring rod and hold beaker up to a 
strong light and looking through it from the bottom and if any ac- 
tion (bubbling or movement) is seen on these impurities, give the 
solution a little more time to dissolve them. Then add another inch 
or so of pure water to save intense heat when acidulating, then add 
25 c.c. strong sulphuric acid C. P. (for ordinary shop work good 
soft clean tap Avater if free from organic matter, and good quality 
commercial acid will do). Stir the acid in. 

Before adding the acid the solution is of a rusty orange color. 
After adding the acid the solution is of a light emerald color. 

Having done this, take a 100 c.c. graduated measuring glass tube, 
with a cock at the bottom, i.e., about Oi^" high and 1%" or 
less in diameter and graduated by centimeters from to 100 c.c, 
and fill it up to the 100 c.c. mark with the permanganate of potash 
solution. 

Graduall}^ pour this into the zinc solution. At first the pink 
color will almost instantly disappear, then go slower and hang 



260 GALVANIZING AND TINNING 

cloudy. Keep stirring all the time until the end, i.e., when the last 
drop or two added and well stirred will just turn the whole solu- 
tion throughout a pale salmon pink. Then stop. Eead off from 
the glass how much of the solution was used and multiply this by 
1.0364. The result will be the actual metallic percentage of the 
zinc dust. 

Example: 49 c.c, of solution used to give the pink color. Then 
49 X 1-0364 = 50.7836 per cent, metallic zinc. Thirty to 40 per 
cent, dust will do with 13 to 15 g. ferric. Over that make sure by 
giving it 20 g. ferric. Excess does not harm. 



CHAPTER XXVII 

Preparing Material and Loading 

THE methods described in the preceding pages of this book, 
for cleaning castings and other material for hot galvaniz- 
ing and turning, are also applicable to material for Sherard- 
izing. with the following exceptions. When cleaning with acid by 
the pickling process, the acid should be thoroughly relieved. 

If a sufficient amount of cast and malleable cast iron are handled 
it might be advantageous to use a sand blast for removing the dirt, 
rust or slag, but when castings form only a part of the work 
they can be treated according to the following specifications. 

Cleaning material l)y sand l)lasting is accomplished by subject- 
ing the material to the impact of fine, clean, dry sand under air 
pressure of 20 to 80 pounds. If the work to be cleaned consists 
of large pieces that can he handled easily, hose al)out 1/4 'to %" 
is used. If the material consists of small articles it is more eco- 
nomical to use a sand blast tumljling barrel. The advantage of 
cleaning material by this method is that all slag or silica scale is 
quickly removed, exposing the clean iron. It also overcomes the 
use of acids, etc., which are very hard to eliminate in porous or bad 
castings. A comprehensive treatment of sand blasting and clean- 
ing in the tumbling barrel is given in Chapter VI. 

Pickling of Steel 

In pickling steel, such as bolts, nuts, washers and scaly material, 
the articles should be thoroughly washed in the lye solution, the 
strength of which must be about 38 pounds of lye to each 100 gal- 
lons of water. Care must be taken that no washed-off oil or fat 
is allowed to float in the tank, and skim as frequently as possible. 
When tlie solution becomes greasy or brownish in color, it should 
be renewed. If the tank is to be kept busy, the renewal should take 
place every other day. Keep the material in the solution from 5 to 
10 minutes, and drain in the basket. If the material is covered 
with dried-out oil, it should remain in the solution for a longer 
time. 

261 



262 GALVANIZING AND TINNING 

Wash in hot Avater and drain. 

Place in the hot sulphuric acid solution long enough until all 
foreign suhstance lias been removed or dissolved (in some cases 
5 to 8 minutes). The strength of this sulphuric acid solution 
should be about 9.5 per cent., in which 13 gallons of 66 per cent, 
commercial sulphuric acid solution should be used to each 76.5 gal- 
lons of water. The pickling qualities of this solution can be de- 
term iiied by its density and its color. A hydrometer should be 
used and the solution should be about 1.315 at 38 deg. C, or 
about 1.110 at 80 deg. C. Tf the solution should happen ta*he 
clear and its density less than the stated value, acid should be 
added to maintain its strength. If the color of the solution changes 
and appears brownish, the solution Ijecomes invalid and should be 
renewed. Drain the material in this solution. 

Wasli in hot water and drain. 

Place in a lime solution, which will neutralize any acid that still 
remains on the material. The strength should be about 20 pounds 
of either quicklime or air slacked lime to each 100 gallons of 
water. When the solution changes from a milky to a brownish 
color it should be renewed. The material should remain in this 
lime solution for at least 5 minutes and then drain. 

Wasli in hot water and drain. From time to time litmus tests 
should be made in this water tank, and when the water shows acid 
reaction it should he renewed. In case fla1:y sediments occur in 
this tank, it is advisable that the drain be opened at different 
periods to remove them, since they are heavier than water and 
cannot be washed out by the inflowing water. Usually the tank 
may be drained twice a day. 

Empty the material on the inclined screen for drying. 

The temperature of the acid and alkali solutions should be 60 
deg. to 80 deg. C. 

The temperature of the water baths should be 70 deg. to 90 
deg. C. 

Fresh running water should be alloAved to enter each water tank 
in order to keep it clean. 

Before each T'encAval of either water, acid or alkali solution, the 
tank should be thoroughly cleansed. 

During the pickling process the baskets of material should be 
shaken and dipped several times into the solution in order that 
the tightly placed material may be benefited by it. 



PREPARING MATERIAL AND LOADING 263 

Pickling Malleable and Gray Iron Castings 

]\ralloal)k' iron line material should ))e thoroughly washed in the 
lye solutiou, the strength of which must l)e ahout 38 pounds of lye 
to each 100 gallons of water. Care must he taken that no washed- 
otT oil or fat is allowed to float in the tank, and skim as frequently 
as possil)le. M'hen the solution becomes greasy or hrownish in 
color, it should he renewed. If the tank is to be kept Inisy, the re- 
newal should take place every other day. Keep the material in 
tlie solution for 5 to 10 minutes, and drain in the basket. If the 
material is covered with dried-out oil, it should remain in the solu- 
tion for a longer time. 

Wash in hot water and drain. 

Place in the hot hydrofluoric acid solution long enough until all 
foreign suljstance has been removed or dissolved. The strength 
of this solution should be about 5 -per cent., in which 15 gallons 
of -30 per cent, commercial hydrofluoric acid should be used to each 
7().o gallons of water. The pickling qualities of this solution can 
be determined by its density and its color. A hydrometer should 
be used and the solution should lie about 1.02G at 15 deg. C, or 
aliout 1.00!) at SO deg. C. If the solution should happen to be 
clear and its density less than the stated value, acid should be 
added to maintain its strength. If the color of the solution changes 
and appears bro^^^lish, the solution Ijecom.es invalid and should be 
renewed. Drain the material in this solution. 

One of the cheapest and most used methods of relieving the acid 
is by rinsing in cold water and then jflacing the material into a 
boiling solution of cyanide (mixture: 1 pound of cyanide crystals 
to SO gallons of water) for ten minutes. Material coming from the 
ordinary pickle placed through this method will insure the reliev- 
ing of all acid. By folloAving this method a bright, clean coating 
of zinc is assured. 

Cup-shaped material should be stacked in the basket in such a 
way as to contain as little acid as possible. In case the material 
should show defective pickling or rust, it should be repickled. In 
case the defects are slight, sand tumbling can be applied for 10 to 
15 minutes. The material should be put into the Sherardizing 
drum as soon as possible after pickling, to prevent oxidation. 

Loading the Drums 

Alternate layers of zinc dust and material should then be placed 



264 



GALVANIZING AND TINNING 



into the container within a few inches of the cover to allow for any 
expansion that may talce place From 3 to 5 pounds of zinc dust 
should be used to each 100 pounds of material. The cover should 
be made dust tight, not air tight, and the container then removed 
to the furnace. 

Fig. 129 shows method of loading a drum up to 6 ft. long. The 
steel loading frame is placed in a dusting pan to catch whatever dust 
may be scattered and lost. The drum is placed on a loading frame 
at an angle of 45 deg. The material is then shoveled or placed in 
the drum with a thorough mixture of zinc, averaging on bolts and 




Fig. 129. Dkum in Position for Loading 

nuts 100 pounds of zinc dust to 200 pounds of material. After 
completely filling the drum, the head is placed in position and 
secured. The cover should fit so as to be dust proof, but nor air 
tight, so that whatever gases form within the drum will come out 
and burn during the operation. The wheels are then placed on the 
hubs and the drum placed onto a transfer car. Care should be 
taken in seeing that the horizontal axis of the drum is in line 
with that of the clutch which revolves it, thereby causing a true 
rotation of the drum; also that the carriage should be firmly held 
within the furnace by means of lock keys. Heat should then be 
applied. 

Another method of loading is to alternate the zinc dust and 
material and only fill to within 6" of the top. 

Fig. 130 illustrates the method of loading from overhead chute. 
This method is highly recommended in cases where pipe, tubing 
and articles are Sherardized up to 20 ft. long, which require a coat- 
ing on the inside as well as the outside. One particular item should 



preparinCt material and loading 



2G5 



not be overlooked in the coiiveYiii<;' of the zinc dust into the clintes 
and hoppers. Due to its density it will paclc very close and a worm 
feed is found necessary to transfer it uniformly from the hopper 
into the drums. The dust used is obtained from the hoods of zinc 
smelters, upon which it is formed by the condensation of zinc 
vapors, and it is not ground commercial zinc, as has been 




Fig. L30. Loading from Overhead Chute 
erroneously stated. The dust usually contains about 85 per cent, 
pure zinc and 10 per cent, of zinc oxide, which latter is not in a 
free state, and, being evenly distributed throughout the mass, pre- 
vents the dust from becoming pasty at the high temperature re- 
quired for Sherardizing. 

In loading 'flat stock it is necessary to have a layer of zinc be- 
tween each piece of metal, uniformly distributed, and the drmns 
should be rotated the same as the cylinder drum. 

As zinc dust is one of the main features in producing good 



266 ' GALVANIZING AND TINNING 

results in the process of Slierardizing-, sjoecial attention shonld be 
given this item. It should be 2:)rocured free from lumps and with 
as little moisture as jjossible, and stored in galvanized cans and 
kept covered when not in use. 

In case the zinc dust is damp and lumpy, it should be placed in 
the cylinders, without any material, drums" filled about one-half 
full, and tlie cover lightly fastened to assure relief of accumulating 
gases, and placed in the furnace at al)out 350 deg. F. for three 
hours. The zinc dust will then be in perfect condition for use, 
after cooling. 

The best results are obtained when the zinc dust has been reduced 
to about 50 23er cent, metallic, and therefore new zinc should be 
reduced to that percentage as rapidly as possible. 

Sherardized material shows a deposit of 4 ^sounds of zinc per 
100 pounds of material treated, as an average. Therefore, once 
it has been reducecl to the right percentage, it can be held at that 
strength Ijy simply adding 4 pounds of new zinc per every 100 
pounds of material treated. See that it is thoroughly mixed. 
A chemical analysis once a week is recommended. 

The aljove stated deposit is sufficient to stand the well-known 
Preece test of four one-minute immersions in saturated solution of 
copper sulphate, IT. S. Government and Western Electric Co.'s test, 
specification No. 13110, dated rel)ruary 3, 1908. 

Packing the Electric-Heated Machine 

Material must be packed in drum in such a way that no vio- 
lent tumbling will occur, else sharp corners or threaded parts will 
be damaged ; neither should it be packed too tight, or a free flow of 
dust and heat will not result and, consequently, poor Slierardizing 
will be obtained. By actual experience in Slierardizing malleable 
iron, which is very porous, it has been found that 400 lbs. of dust 
_to any load, ranging from 400 lbs. to 1,800 lbs. of niiiterial, can 
be used. This consists of 360 lbs. of used dust and 40 lbs. of 
new Grasselli dust. When small material is packed in individual 
receptacles to be placed inside of Sherardizing drum, a proportion 
of about 5 lbs. of dust to 100 lbs. of material is used. The dust 
should be mixed in a tumbling barrel or Sherardizing drum and 
sifted through an 80 :1 mesh riddle before charging the drum. 

Before putting cover on drum an asbestos wicking basket is 
put under cover to make drum as nearly air tight as possible. 



CHAPTER XXVIII 

Temperature and Duration of Heats 

TEMPEEATURE and time are factors which, depending 
upon each other, are very important in the process of 
Shorardizing. They depend on the choice and quality of 
zinc dust used and also on the requirements and physical prop- 
erties of the Sherardized material. 

If common or blue dust is used, the total run is to be about 5I/2 
hours, of which aliout 2 hours must be allowed for attaining a 
maximum furnace temperature of 440 deg. C. and about 3I/2 hours 
for a temperature of 440 to 450 deg. C. The metallic percentage 
of zinc should be from 35 to 45 per cent. The drum should be 
rotated throughout the whole run at about 1/2 i'- P- i^^- 

In case Grasselli dust is used, the strength should l)c 40 per 
cent, and upward. The total run should be 91/^ hours, of which 
2 to 2V^ hours must be allowed for attaining a maximum furnace 
temperature of 385 deg. C. and 7 to 7Vli hours for a temperature of 
385 deg. C. The container should be rotated the same as for blue 
dust. 

At the end of the run the container, if ])lue.dust is used, should 
be removed from the furnace and not opened until the temperature 
has dropped to 100 deg. C. This will require 8 to 24 hours, de- 
pending upon the outside temperature. In the case of Grasselli 
dust the container can be opened at a somewhat liigher temperature. 
No cooling must be done by application of water or moisture. 

Thickness of Coating 

Careful attention must be given to see that the dimensions of 
articles, as bolts or nuts, should be such as to allow for enough 
clearance for the various kinds of coatings. These dimensions, 
where in normal cases the test is from 4 to 8 dips, should have an 
allowance for a coating of 0.001" to 0.002". For example, if a 
pin for drive fit is to be Sherardized, the difference in diameter 
between the pin and hole before treatment should be 0.006" to 
0.008" if both surfaces are Sherardized. 

The General Electric Co. in Sherardizing their material deposit 

267 



268 



GALVANIZING AND TINNING 



.0025" on a side or a total of .005" on a diameter. Where threaded 
parts are to be Sherardized they are imdercut or overcut, as the 
case may be, to allow for this deposit. Complete tables of sizes 
are given in Tables I to IV. 

In case of Sherardized parts containing holes and pieces fitting 
these holes, the allowance for Sherardizing is made in the hole, 
in other words, the hole is made .010" larger. This increase in 
deposit is equivalent to .85 to 1.1 oz. per square foot. 

In every case material Sher- 
ardized as per above will stand 
170 hours as a minimum in a 
salt spray without showing dis- 
coloration due to corrosion of 
the iron, and may endure the 
spray even very much longer. 
This is considered the most sat- 
isfactory and rational test on 
Sherardizing. Some very inter- 
esting facts regarding the va- 
rious tests arc given in chapter XXXII. 

Where body-bound bolts are used body of bolt should be made 
to size and allowance made in hole to allow for Sherardizing. Nuts 
to be Sherardized should be tapped .005" larger than standard. 

^ TABLE I 

BOLTS AND SCREWS ( U. S. STD. ) 



Equal..^,^^^ 




-RooVDia- ■- 

-■PifdhDiCF--- 

e OufsideDia -■ 

Allowable Variation m the 
Pitch per foot ^i^. 010" 

Fig. 131 



%" 
Vm 
V2" 

%6' 

%" 
3/4" 

%" 
1" 

lys" 
11/4" 

i%" 
1Y2" 

Ws" 
l%" 

1%" 
2" 



-20 

-18 
-16 
-14 
-13 
-12 
-11 
-10 

- 9 

- 8 

- 7 

- 7 

- 6 

- 6 

- 51/2 

- 5 

- .5 

- 41^ 



Outside Die 


. 


Pitch Dia. 




Root Dia. 


Min. 


Max. 
.250 


Dif. 
.005 


Min. 


Max. 


Dif. 


Min. 


Max. 


.245 


.2151 


.2176 


.0025 


.1801 


.1851 


.3075 


.3125 


.005 


.2740 


.2765 


.0025 


.2353 


.2403 


.370 


.375 


.005 


.3319 


.3344 


.0025 


.2888 


.2938 


.4325 


.4375 


.005 


.3886 


.3911 


.0025 


.3397 


.3447 


.495 


.500 


.005 


.4476 


.4501 


.0025 


.3951 


.4001 


.5565 


.5625 


.006 


.5054 


.5084 


.003 


.4481 


.4541 


.619 


.625 


.006 


.5630 


.5660 


.003 


.5009 


.5069 


.744 


.750 


.006 


.6821 


.6851 


.003 


.6141 


.6201 


.869 


.875 


.006 


.7999 


.8029 


.003 


.7247 


.7307 


.994 


1.000 


.006 


.9158 


.9188 


.003 


.8316 


.8376 


1.117 


1.125 


.008 


1.0282 


1.0322 


.004 


.9314 


.9394 


1.242 


1.2.50 


.008 


1.1532 


1.1572 


.004 


1.0564 


1.0644 


1.367 


1.375 


.008 


1.2628 


1.2668 


.004 


1.1505 


1.1585 


1.492 


1.500 


.008 


1.3878 


1.3918 


.004 


1.2755 


1.2835 


1.617 


1.625 


.008 


1.5029 


1..5069 


.004 


1.3808 


1.3888 


1.742 


1.750 


.008 


1.6161 


1.6201 


.004 


1.4822 


1.4902 


1.867 


1.875 


.008 


1.7411 


1.7451 


.004 


1.6072 


1.6152 


1.992 


2.000 


.008 


1.8517 


1.8557 


.004 


1.7033 


1.7113 



Dif. 

.005 
.005 
.005 
.005 
.005 
.006 
.006 
.006 
.006 
.006 
.008 
.008 
.008 
.008 
.008 
.008 
.008 
.008 



TEMPERATURE AND DURATION OF HEAT 



269 



TABLE II— SIIERARDTZED 



ROLTS AND SCREWS 



DIMENSIONS BEFORE SHERARDIZING 



s 




Outside Dia 




Pitch Dia. 


Root Dia. 


ize 


Min. 


Max. 


Dif. 
.005 


Min. 


Max. 
.2126 


Dif. 
.0025 


Min. 
.1751 


Max. 


Dif. 


1/i" 


-20 


.2400 


.2450 


.2101 


.1801 


.005 


■'/m< 


-18 


.3025 


.3075 


.005 


.2690 


.2715 


.0025 


.2303 


.2353 


.005 


■}8 


-16 


.3650 


.3700 


.005 


.3269 


.3294 


.0025 


.2838 


.2888 


.005 


■'Ifl' 


-14 


.4275 


.4325 


.005 


.3S36 


.3861 


.0025 


.3347 


.3397 


.005 


lo" 


-13 


.4900 


.4950 


.005 


.4426 


.4451 


.0025 


.3901 


.3351 


.005 


»'1fi' 


-12 


.5515 


.-5575 


.006 


.5004 


.5034 


.0030 


.4431 


.4491 


.006 


W^' 


-11 


.6140 


.620 


.006 


.5580 


.5610 


.0030 


.4959 


.5019 


.006 


•Vi" 


-10 


.739 


.745 


.006 


.6771 


.6801 


.0030 


.6091 


.6151 


.006 


'/.s 


- 9 


.864 


.870 


.006 


.7949 


.7979 


.0030 


.7197 


.7257 


.006 


1" 


- 8 


.989 


.995 


.006 


.9108 


.9138 


.0030 


.8266 


.8326 


.006 


Hi" 


- 7 


1.112 


1.120 


.008 


1.0232 


1.0272 


.0040 


.9264 


.9344 


.008 


lVi" 


- 7 


1.237 


1.245 


.008 


1.1482 


1.1-22 


.0040 


1.0514 


1.0594 


.008 


1%" 


- 6 


1.362 


1.370 


.008 


1.2578 


1.2618 


.0040 


1.1455 


1.1535 


.008 


n/o" 


- 6 


1.487 


1.495 


.008 


1.3828 


1.3868 


.0040 


1.2705 


1.2785 


.008 


i%" 


- 51:^ 


1.612 


1.620 


.008 


1.4979 


1.5019 


.0040 


1.3758 


1.3838 


.008 


l-V," 


- 5 


1.737 


1.745 


.008 


1.6111 


1.6151 


.0040 


1.4772 


1.4852 


.008 


17,«" 


- 5 


1.862 


1.870 


.008 


1.7361 


1.7401 


.0040 


1.6022 


1.6102 


.008 


2" 


- 41/0 


1.987 


1.995 


.008 


1.8467 


1.8507 


.0040 


1.6983 


1.7063 1 .008 



TABLE III 



MACHINE SCREWS (A.S.M.E. STD. ) 



Outsid: Dia. 



Pitch Dia. 



Root Dia. 



Size - 


Min. 


Max. 
.060 


Diff. 
.0028 


Min. 
.0505 


Max. 
.0519 


Diff. 


Min. 
.0410 


Max. 


Diff. 


0-80 


.0572 


.0014 


.0438 


.0028 


1-72 


.0700 


.073 


.0030 


.0625 


.0640 


.0015 


.0520 


.0550 


.0030 


2-64 


.0828 


.086 


.0032 


.0743 


.0759 


.0016 


.0624 


.0657 


.0033 


3-56 


.0955 


.099 


.0035 


.0857 


.0874 


.0017 


.0721 


.0758 


.0037 


4-48 


.1082 


.112 


.0038 


.0966 


.0985 


.0019 


.0807 


.0849 


.0042 


5-44 


.1210 


.125 


.0040 


.1082 


.1102 


.0020 


.0910 


.0955 


.0045 


6-40 


.1338 


.138 


.0042 


.1197 


.1218 


.0021 


.1007 


.1055 


.0048 


8-36 


.1.596 


.164 


.0044 


.1438 


.1460 


.0022 


.1227 


.1279 


.0052 


10-30 


.1852 


.190 


.0048 


.1660 


.1684 


.0024 


.1407 


.1467 


.0060 


12-28 


.2111 


.216 


.0049 


.1904 


.1928 


.0024 


.1633 


.1696 


.0063 


14-24 


.2368 


.242 


.0052 


.2123 


.2149 


.0026 


.1808 


.1879 


.0071 



TABLE IV— SHERARDIZED 

MACHINE SCREWS 



DIirENSIONS BEFORE SHERAEDIZING 



Outside Dia. 



Pitch Dia. 



Root Dia. 



Size - 


Min. 


Max. 


Dift-. 


Min. 


Max. 


Diff. 
.0021 


Min. 


Max. 


Diff. 


6-40 


.1288 


.133 


.0042 


.1147 


.1168 


.0957 


.1005 


.0048 


8-36 


.1546 


.159 


.0044 


.1388 


.1410 


.0022 


.1177 


.1229 


.0052 


10-30 


.1802 


.185 


.0048 


.1610 


.1634 


.0024 


.1357 


.1417 


.0060 


12-28 


.2061 


.211 


.0049 


.1854 


.1878 


.0024 


.1583 


.1646 


.0063 


14-24 


.2318 


.237 


.0052 


.2073 


.2099 


.0026 


.1758 


.1829 


.0071 



270 



GALVANIZING AND TINNING 



When the article Sherardized will be subjected to sharp bending 
or to considerable variations of temperature, the thickness of coat- 
ing will be limited, for zinc, being more brittle and having a dif- 
ferent coefficient of expansion than iron, will separate from the 
iron under these extreme conditions if too thick a coating is applied. 

Temperature an Important Factor 

As mentioned before, the effect of temperature is an important 
factor in both elements o£ the process, as the iron, with the increase 
of temperature, increases its power of absorption of zinc vapor and 
likewise the vapor tension of zinc increases with the temperature. 
According to authorities on vapor tension, with an increase of 



j006 




Chart I. 



200 240 280 320 360 400 440 480 
Degrees C. 
Rate of Deposit and Temperature in Electric Heated 
Sherardizing Machine 



temperature from 325 to 375 deg. C, the relative vapor tension 
increases 14 times, and from 325 to -125 deg. C, the relative vapor 
tension increases 92 times. The absorption of zinc vapors by Vari- 
ous metals (copper, nickel and iron) approaches the same rate at 
high temperatures up to about the melting point of zinc. Above 
this the absorption is exceedingly rapid. 

From curves obtained by A. E. Johnson and W. E. Woolrich, it 
is seen that the greatest variation of al)Sorption with a variation of 
temperature lies near the melting point of zinc, thus a fluctuation 
of loAA'-er temperature does not affect the absorption of the zinc 



TEMPERATURE AND DURATION OF HEAT 



271 



vapor to tlie i^anic extent as at higher temperatures. In other 
words, more uniform absorption of zinc vapor is obtained at lower 
tenijieratures. 

In view of the above facts it appears tliat wlien a metal is lieatcd 
in the presence of the vapor of another metal, or the vapor of other 
elements or compounds, the metal evolves a portion of the gases or 
vapor which it contains, and in exchange accommodates the precipi- 
tation of the other vapors within its pores. 

Operation of the Electric Heated Drum 

The drum is started revolving at about f to 1 r.p.m. and switch 
thrown to "high heat." The high heat is used to bring drum up 
to desired temperature (350 deg. to 375 deg. C.) to give correct 









































































































































































































































) 






i_ 
















































































































































ouu - 




























































































































































































































































































































































































^uu - 
























































































































































o 












/ 














" 


*«• 


^ 
























































t 
























^ 










































5 "^nn 










( 




























■^ 


^ 




































m 








J 




































■*« 
































^ 








1 








































^ 


k, 


























Q 






/ 
















































>> 


^ 


























/ 




















































^ 


*« 
















'^nn 
































































k 












C.UU 




/ 
































































N 


»v. 
















































































■-v 




1 




























































































/ 










































































ton 


/ 












































































' 






















































































































































1 


1 










































































f 












































































n - 
























— 1 





















































50 



40 

I 

20 



10 



I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 Id 19 
Hours Run 

Chart II. Temperature and Power Curve of Electric-Heated Sher- 
ARDiziNG Machine 24" x 24" x 40" 



deposit, and then the low heat is thrown on to hold it at that tem- 
perature for the required period (2^ to 3 hours) to give the de- 
posit. After this current is thrown off and drum allowed to cool 
to 180 deg. C, which is a safe temperature to open drum. This 
should apply to Grasselli zinc only, as blue dust Avill fuse more 



272 GALVANIZING AND TINNING 

rapidly. Charts I and II provide interesting records of the power, 
temperature and deposit. 

Sherardizing with Zinc Under Vacuum 

After reading the above it is clear that to do Sherardizing we 
should have the zinc vapors at their greatest tension and have Sher- 
ardized iron in condition to give off the maximum gases. Zinc boils 
under ordinary pressure at 913 deg. C, and the boiling point under 
vacuum is reduced to 548 deg. C. Iron on being heated from 500 
to 600 deg. C. in vacuum gives off gases readily. Therefore, it is 
quite clear that in vacuum the conditions are best for Sherardizing, 
and the writer was able to produce condensation of zinc on iron 
in a very short time. Some of the results were obtained under these 
conditions in minutes, where with ordinary. pressure under the same 
conditions it required hours. This process and the machine for 
treating material by this method have been covered by patents. 

The process is not necessarily dependent on having the substances 
supplying the vapor in the form of a powder, although a substance 
in this form may often be raised to a temperature above the melting 
point without fusing the articles together. The elevated tempera- 
ture which can thus be secured is of material assistance in securing 
a rich vapor, which naturally hastens the process and therefore is 
an advantage in many cases. A further advantage of using the 
material supplying the vapor in the powdered form is the .enor- 
mously increased surface which can thus be secured, thus giving a 
richer vapor, since the amount of material vaporized at a given 
temperature and pressure increases with increased evaporating sur- 
face. This is particularly of value when the boiling point of the 
vapor-giving material is above the temperature at which the deposi- 
tion occurs. 

Time an Important Factor 

Just as temperature, so time is an important factor in the process 
of Sherardizing. Since articles of different size, shape and char- 
acter are treated, if each were given its ideal condition of tempera- 
ture and quality of zinc dust, the time of treatment of all would be 
alike, but this is not practical, for it is easier to vary the time of the 
process than the other factors. 

It is possible to obtain almost instantaneous Sherardizing in the 
case of wire heated to a high temperature and allowed to pass 



TEMPERATURE AND DURATION OF HEAT 273 

through zinc dust at normal temperature. In the case of many 
articles to be Sherardized tliis method is impractical and so longer 
periods of time are required. Not only the time of heating the 
article during the process should be considered but also the time of 
cooling, for this j)rocess is not confined to any one particular tem- 
perature, but takes place over a wide range of temperature. If the 
articles being treated have not become saturated during the heating 
period, the process will still continue upon cooling, until the tem- 
perature falls below its minimum point. There are two reasons for 
slowly cooling: First, to prevent loss from exposing hot zinc dust 
to the atmosphere (the metallic zinc particles would quickly oxi- 
dize) ; second, to prevent the articles being chilled too quickly. 

Motion During Sherardizing 

The general iDublic has been given to understand that this is a 
tumbling process, and that the zinc will not deposit unless the 
drums are continuously rotating. If the articles are thoroughly 
mixed with the dust, it is not necessary to have the drums continu- 
ously rotating to insure uniform deposit, providing that the drums 
are not over 20 in. in diameter. An occasional turn of once in 15 
minutes is ami^le to insure good results; too much rotating under 
heat pressure will make the articles appear dark and dusty. 

Sherardizing can be and is being done where the articles to be 
treated are placed in the zinc dust, heat applied, but no motion 
given to either the dust or the articles during the process. This 
method is used in the case where large pieces, plates and sheets are 
being treated. If the transmission of heat through zinc dust were 
perfect and if the deterioration of the zinc particles were negligible, 
the motion of the articles during treatment would be unnecessary. 
Such, however, is not the case, for zinc dust is a poor conductor of 
heat and the deterioration of the zmc particles in intimate contact 
with the article treated requires a replacement of the same by new 
particles. Since this process continues during the cooling period, 
until it reaches its critical point, where it ceases, the motion will 
produce the same efl-'ect then as during the heating period. 

Zinc dust, which is commonly called blue powder, is a flue dust 
and therefore a by-product of the zinc smelting furnace known as 
the Belgian furnace. It contains, as a rule, from 75 per cent, to 
90 per cent, pure zinc. The supply is ample at a price a fraction 
above that of spelter, and it can be procured in any quantities that 



274 GALVANIZING AND TINNING 

may be required. The nature of the zinc, which is given off at a 
temperature of 1,000 deg. C. or more at the inception of distilla- 
tion, comes into contact with the comparatively cold atmosphere of 
the flue and the sudden chill causes a rapid condensation of the 
vapor, so rapid, indeed, that it skips the liquid state and drops into 
the shape of perfectly spherical articles, of which about 30,000,000 
can be crowded into a cube measuring 1/16" in every direction. 
This impalpable powder, notwithstanding its high specific gravity, 
for it is only about 10 per cent, lighter than pure zinc, can be 
blown about like lycopodium. It is used very extensively by textile 
manufacturers for dye work, and by paint manufacturers, and is 
sold packed in barrels holding about 1,500 pounds. It cannot be 
melted into slabs on account of its rapid oxidation at a very low 
temperature. The peculiar properties of zinc dust have been 
ascribed by some to the presence of cadium which, being of more 
volatile metal, is distilled first from ore and then condensed into 
flues. One observer finds quantities ranging from 0.283 to 0.794 
per cent, in flue dust after two hours of furnace operation. Others 
have claimed that these properties are due to the presence of zinc 
oxide or other impurities. Most of the zinc is purchased in Belgium 
or Silesia. Silesian zinc has been found the best adapted for Sher- 
ardizing, due to the fact that it has less moisture. A sample of an 
analysis showed the following : 

Metallic zinc 88.95% Cadium 0.62% 

Zinc oxide 6.88% Sulphur 0.055% 

Lead 3.45% Iron 0.04%, 

A fact that is undoubtedly responsible in a great measure for the 
mystery attaching to the action of zinc dust is its readiness to 
oxidize. It is only when oxidation is put out of its power, as in 
the closed Sherardizing drum, that heat will produce sufficient over- 
strain to cause the jiarticle to burst into vaporized gas. This gas, 
so suddenly released, will condense instantly on the coolest spaces 
it can find. In Sherardizing, the coolest spaces are on the articles 
in the drum. 

It is an established fact that in Sherardizing the presence of 
zinc oxide is necessary. We might suppose, therefore, that a mole- 
cule of oxide is reduced to voltaic action when it comes into con- 
tact with the iron. The zinc attaches itself to the iron, which acts, 
therefore^ as a cathode in electrolysis, £ind the oxygen travels in the 



TEMPERATURE AND DURATION OF HEAT 275 

opposite direction, comhinos with a free molecule of zinc to form 
a molecule of oxide, ami i^oes through the same performance as 
before. 

Zinc dust appears to break down into vapor at al)0ut 150 to 200 
deg. C, although it nn(loul)tedly begins to disintegrate at a 
lower heat. As the pressure increases it takes a greater amount of 
heat to cause the breakdown. As the vapor condenses the pressure 
is relieved and the hotter articles of dust are vaporized and re- 
establish an equilibrium. 

Being a gas, the zinc vapor can force itself into the pores of the 
metal and form a deposit to a dejDth which will increase with the 
duration of the treatment. 

Bapid cooling will cause the zinc to condense as crystals, the ad- 
herence of which to the iron is, however, inversely proportional 
to their size. Normal cooling would seem to yield in all cases a 
fine, glossy surface of what can be appropriately termed ferrozinc. 

General Operation 

There are three factors to contend with in the process of Sher- 
ardizing, viz., zinc dust, temperature, and the length of time the 
heat is run. 

For example, take a standard size cylinder or drum 15" to 20" 
in diameter, i/j^" wall, new zinc dust at 90 per cent, metallic, tem- 
perature 750 deg. to 950 cleg. F. outside of drum, with pyrometer 
stem showing at the bottom of the drums and protected from the 
flame by a baffle plate, the furnace started cold and allowing two 
hours to bring the temperature up to the required number of 
degrees and held at that point for three hours, should give good 
results. If, however, the deposit should not be sufficient, then the 
temperature should be slightly increased, say 25 deg. or the 
time of operation extended; but rules generally followed to 
compare with the ordinary ten hour per day time is to increase the 
temperature, which applies to ordinary material only. In cases 
where high tempered steel or spring stock is treated the time of 
operation should be extended and the temperature reduced to about 
650 deg. F. for a 15" drum and 700 deg. F. for a 20" drum. The 
drums are then taken out and allowed to cool (under no circum- 
stances should the drums be opened while hot, as the zinc dust will 
fuse and burn). 

The time generally allowed for heats on ordinary material is 



276 



GALVANIZINa AND TINNING 



five and a half hours for the first heat, started from a cold furnace, 
and four and a half hours for the second heat, which allows one- 
half hour for making the change. 




Fig. 132. Unloading into Rotaky Dust Separator 

After loading, the drums are sealed and rolled into the Sher- 
ardizing furnace, as shown in Fig. 119 or 128. Here they remain 
for 5 to 6 hours, according to the tonnage that they contain, in an 
evenly maintained temperature of 780 deg. F. 

Cooling and Unloading 

Upon removal from t]ie Sherardizing furnace the drums are 
rolled out on the cooling platform, as shown in Fig. 120 or 128, 
and allowed to cool out, as it is called, for 12 to 16 hours before 



TEMPERATURE AND DURATION OF HEAT 27? 

tliey are unsealed, as the introduction of oxygen to the zinc while in 
a superheated state would, of course, destroy it. The annealing in- 
cident to the slow heating and slower cooling through which articles 
pass in the process makes Sherardizing doubly valuable as a finish 
for steel products which, like electrical conduits, must be bent 
during installation, and for many cast-iron articles which would 
otherwise require a separate operation for the purpose. 

After "cooling out" the contents of the drums are dumped into 
large hoppers, as shown in Fig. 132, and the surplus zinc dust 
rocked out, leaving, in addition to the zinc-iron alloy, an exterior 
coating of zinc. 



CHAPTER XXIX 

Don'ts in Sherardizing Practice 

THE following account of the inspection and reorganization 
of a Sherardizing plant is included so the users of this hook 
may profit hy the experience of others and use the many 
valuable suggestions it contains in their own practice. 

The plant was installed for the purpose of Sherardizing ma- 
terial for their own product. The material included bolts, nuts, 
malleable iron castings and line material. When the plant was in- 
stalled the men in charge of the plant knew practically nothing 
about the process. Sherardizing was done in the same room with 
pickling and hot galvanizing. The steam and acid fumes from the 
large pickling tanks (used for pickling large castings preparatory 
to painting) not only had a deleterious effect upon the Sherardiz- 
ing process, but also in connection with the zinc dust in the air, 
made working conditions almost intolerable. Whenever articles 
were pickled in large quantities they were first placed in an empty 
acid tank and the acid and water poured over them until covered. 
When, on inspection, the pickling process was completed, the acid 
was allowed to run into the sewer. Before all of these pickled 
articles could l)e washed off most of them had acquired a thin 
coating of rust which necessitated another dip in the acid before 
being Sherardized. No unloading pit liad been provided, the dust 
being dumped upon the floor to be trampled under foot and, on sev- 
eral occasions, to be flooded by water. Tlie ovens, too, were not 
suita1»le for the work. The clutches wliich connected the drums 
with the driving mechanism were crude and clumsy so that they 
could not be applied from outside. Tliis necessitated cooling of 
the ovens to allow a workman to enter the oven to attach a clutch. 

Considerable trouble had been encountered by the dust caking 
and balling in the drums. This became so bad at times that nearly 
a whole drum of work would be scrapped and much dust wasted. 
This condition was practically eliminated by confining the dust 
in a bin away from all water or acid vapors, as well as keeping the 
temperature within the limits for the particular dust used. The 
large pickling tanks and paint tank were removed from the build- 

278 



DON'TS IN" SHERARDIZING PRACTICE 279 

ing, giving more room, improving working conditions consi(leral)ly 
and especially reducing the amount of acid fumes coming in con- 
tact with the zinc dust. 

Eliminating Black Spots on Finished Work 

One of the principal difficulties was the elimination of black 
spots on the finished work. At times this became very excessive, 
not only detracting from the appearance of the work but also re- 
ducing the number of dips the material would stand under test. 
Two principal causes were found for this fault. The first was the 
presence of "Tjurnt in" slag in the corners or crevices of the ma- 
terial which it was almost impossible to remove by pickling in some 
instances. This was corrected by more intelligent inspection of 
the material, both before and after pickling. In connection with 
inspection, it was found that the material received practically no 
inspection before treatment. Whenever slaggy material reached 
the Skerardizing department, the inspector was notified and it was 
often found that the material had been removed from the foundry 
more than two years before. An entirely new system of inspection 
has since been adopted, which has taken care of the black spots 
from this cause. 

The second cause was the presence of acid in the spongy or por- 
ous parts of a casting which was not thoroughly washed out or 
neutralized. It was difficult to obtain castings without some por- 
ous parts or corners that were filled with fine cracks, but by careful 
attention to pickling and neutralizing the black spots were re- 
duced to a minimum. 

Obviating Non-Uniformity of Coating 

Another fault was the non-uniformity of coating even with the 
same kind of material in the same drum as shown by testing some 
of the material from difl'erent parts of the drum. A heat analysis 
of the furnaces showed a variation of temperature. This affected 
the uniformity of coating considerably, notwithstanding the drums 
were rotated through the run. This fault was corrected by putting 
new baffles in the furnace, additional heat insulation on the doors, 
and new burners, which gave more uniform distribution of heat. 
New clutches were also included in the general overhauling of the 
furnaces, which allowed the driving mechanism to be connected to 
the drums from outside the furnaces. 



280 ■ GALVANIZING AND TINNING 

In order to save the excessive waste of acid eight small pickling 
tanks were installed, together with sufficient baskets for liandling 
the material. An electric hoist was installed for handling the 
baskets of material from one tank to another. By this betterment 
the quality of pickling was improved as well as reducing the amount 
of supervision required because of systematizing the process. By 
handling the material in smaller quantities during pickling it was 
found that better insjDection was possible. 

Some difficulty was encountered in the case of one particular 
malleable iron article, or cap, which was swedged on the end of a 
wooden rod. In this case the Sherardizing must be done before 
the iron cap was formed on the rod. Whenever the Sherardizing 
was heavy this forming process would cause the cracking or peeling 
of the coating. By increasing the temperature and decreasing the 
time of the process (using blue dust) the quality of the coating 
was much impi'oved. In this way the Sherardized articles would 
stand the same number of dips test with a much thinner coating 
and would retain their coating through the forming |)rocess. 

Improving Psychological Condition of Men 

In this connection the improvement in the psychological condi- 
tion of the men cannot he overlooked. Under the adverse condi- 
tions the men, including those in charge, were very skeptical of the 
process. By explaining the process to them and investigating each 
part of the process with their co-operation it was found that much 
could be accomplished. This was done by improving the unbear- 
able working conditions, as well as those having a direct bearing 
upon the process. Since these improvements were made this plant 
has been doing as good work as any others, while still further im- 
provements would probably increase the convenience and lessen the 
cost of the process. This is an example of what has been done in 
one case to improve a plant aud may be a means of helping others 
to overcome their difficulties, who have had the same or similar 
conditions to contend with. 

It must be understood that zinc penetrating the metal is bound 
to bring to the surface all impurities and, while it does not inter- 
fere with the rust proofing qualities of the article, it makes it 
objectionable in appearance. The claim has been made that articles 
coming direct from the machine, covered with oil, can be Sherard- 
ized without cleaning. This is true where no fats are used with the 



DON'TS IN SHKRARDIZING PRACTICE 281 

oil. In case of fats where tlie zinc will al)sorl) it, it will redeposit 
these fats on tlie surface in the form of oxides, which lias heen mis- 
taken in some instances for rust, as the appearances are very nearly 
alike. The two main fats used in oil for cutting down threads 
are ])ean oil and cotton seed oil. In case of clean oil, free from 
fats, with the zinc of sufficient strength to force its way through 
and ahsorh the oil, no special cleaning is required, l)ut experiment- 
ing along these lines brings out the work dark. This also is an 
objectionable feature and tlierefore has not been found practicable 
when considering the small cost of cleaning. 

Caution 

Careful attention must be given to see that the dimensions of 
the l:)olts and nuts shall be such as to allow for enough clearance 
for the various kinds of zinc coating. These dimensions, where in 
normal cases the test is from 6 to 8 dips, should have an allowance 
for 8 to 9 mils. 

Don'ts 

DON'T de|)osit or 8 pounds of zinc to make the article rust 
proof. Four pounds is sufficient, as too heavy a deposit will render 
the coating brittle and it will flake. 

DON'T take it for granted that just because you have a nice, 
bright color it is rust proof. Test it and find out, as colors are 
very deceiving. 

DON'T luix your floor sweepings in with your zinc. Save it and 
sell it, as the zinc dust in continuous contact with iron will gather 
dirt quickly enough. 

DON'T leave sawdust and excelsior on the work to mix with the 
zinc as it will oxidize and darken the zinc and the material. 

DON'T let 3^our zinc dust stand around in open boxes or barrels 
as it will absorb moisture. Keep it in galvanized cans and covered. 

DON'T throw water on zinc in case of fire as same will produce 
gas. Smother it with a blanket or sand. 

DON'T get scared if you should look into the furnace and see 
fire around the cracks of your drums. It will stop as soon as the 
gas obtained from the moisture is burnt out. 

DON'T open the drums until they are cold, or at least 150 deg. F. 

DON'T expect Sherardizing to fill an uncalked seam. It is 
not a solder. 



CHAPTER XXX 

Coloring and Finishing Sherardized Articles 

BY BUFFING the surface on a fine polishing wheel and 
afterwards placing it on a cloth wheel for color, a finish 
can be obtained which is more brilliant than nickel 
plating, comparing very favorably with silver plating, and 
which will not tarnish. The article Sherardized is a frac- 
tion darker and more velvety in appearance, due to the zinc 
coating, where nickel is a white coating. When cutting down 
for this finish the impression generally carried is that all the 
zinc is being ground off and relieved from the surface. This is not 
the case, due to zinc alloy, and if closely inspected a fine zinc coat- 
ing will show, even through the most brilliant finish, and there is 
perfect rust protection, so long as this veining is visible to the 
naked eye. Further, the friction from a wheel caused in burnish- 
ing ap the surface has a tendency to increase the crystal hardness 
of this coating so that it further resists weather action. 

By taking a piece of cold rolled steel and Sherardizing it to a 
thickness of .001i/i>", and passing it through the rolls cold and 
breaking it down twice its length, it will still show the same resist- 
ance against copper sulphate tests as before this reduction was 
made. This goes to prove that the more friction that is brought to 
bear, as previously stated, the more resistance against corrosion. It 
has also been found that material can l)e top finished in nickel, 
brass, copper and bronze, also can be readily japanned, enameled, 
and painted. 

In the case of copper and 1)ronze, after plating, the material 
should be set aside and let stand for forty-eight to seventy-two 
hours, for action between zinc and copper or l)ronze. This action 
makes the surface appear very dark ])ut, after this action ceases, 
the work is then placed on a buffing wheel for coloring and no 
further action takes place. In the case of japanned coating it is 
recommended that the first dip be made in a solution of about 50 
per cent, benzine and 50 per cent, japan. This thin coating insures 
a perfect body. This is baked on very hard and the second dip 
should be a heavier coating. 

282 



COLORING AND FINISHING SHERARDIZED ARTICLES 283 

For lacquer finish no special operation is necessary, as it will de- 
posit as readily as on the plain material. If a smooth surface is 
required simply buff the article on a cloth Avheel or scratch Inrush 
before finishing. 

This ap]ilies to large articles which cannot be tum1)led. To ob- 
tain tlio smooth surface on small articles for plating or for other 
purposes, they are placed in a tumbling barrel. For dry tuml)ling 
use leather meal or leather chips, operation extending anywhere 
from two to ten hours. For wet tumbling use shot on light ma- 
tciial only. 



CHAPTER XXXI 

Cost of Sherardizing Material per Ton with 
Different Fuels 

A GAS burning furnace does not require the heavy re- 
inforcement that an oil burning or a coke furnace 
■ requires because it is not under as much pressure. 
It has further been found that gas burning furnaces are easier 
to operate but more expensive. Fuel oil and coke are the 
cheapest known fuels in the East. Where natural gas is available, 
this by far is the cheapest fuel. The ordinary wear and tear on 
these furnaces is very small, due to the fact that less than 1000 
deg. F. is required. It should be understood that as little structural 
iron should be used on the inner part of the furnace as possible, to 
keep from warping. A coke burning furnace requires about 3000 
more brick than the ordinary oil and gas furnace, due to the fact 
that the fire box must be thoroughly reinforced for high pressure 
heating and retaining of heat, but with this equipment there are 
no extra installations such as producer gas machines and fuel oil 
machines necessitate. 

Sherardizing is like annealing in that it requires a small amount 
of labor, and that unskilled labor, placed under proper supervision, 
can operate the plant as successfully as a high priced laborer: 

Cost for Fuel Oil Burning 

Per ton 
Fuel oil, one gallon per hour per burner, 3 burners per fur- 
nace, 30 gals, per day of 10 hours, at 5c per gal $1.50 

Zinc dust, average deposit 4 lbs. per 100 lbs. of material 
treated, 80 lbs. per ton, at $5.75 per 100 lbs., average 

market price 4.60 

Labor, two men at 15c per hour, which includes the labor for 

cleaning, pickling, packing, etc 3.00 

Total $9.10 

284 



COST OF SHERARDIZING MATERIAL PER TON 285 

Producer Gas 

Per ton 
riynn & Dreft'ein's guarantee, cost averaged at the rate of 

80 lbs. Pea Coal, equivalent to 1,000 feet of illuminating 

gas, at 75c per 1,000; consumption of furnace 4,000 ft. 

per day would ho 320 11 .s. of coal, at $4.50 per ton $0.72 

Zinc dust, average deposit 4 1I)S. per 100 ll)s. of material 

treated, 80 lbs. per ton at $5.75 per 100 lbs 4.60 

Labor, 2 men at 15c per liour, wliiuh includes labor for clean- 

"ing and pickling, per ton 3.00 

Total $8.32 

Coke 

Per ton 

ColiCj 8 bu. per day at 10c per bu $0.80 

Per ton 
Zinc dust, average deposit 1 lbs. per 100 llis. of material 

treated, 80 lbs. per ton, at $5.75 per 100 lbs 4.60 

Labor, 2 men at 15c per liour, which includes laljor for clean- 
ing and pickling 3.00 

Total $8.40 

Illuminating Gas 

Per ton 

Gas, 4,000 ft. at 75c per 1,000 $3.00 

Zinc dust, average deposit 4 lbs. per 100 lbs. of material 

treated, 80 lbs. per ton, at $5.75 per 100 lbs 4.60 

Labor, 2 men at 15c per hour, which includes labor for clean- 
ing and pickling 3.00 

Total $10.60 

This being a patented process a royalty of $2.50 per ton must 
be added for the cost for every ton of material treated. With a 
large capacity plant the above cost would be less, due to saving 
both in fuel and labor. 

Disposal of Used Zinc or Zinc Residue 

When sufficient amount of zinc oxide has accumulated with the 
zinc to warrant disposal, discontinue the adding of new zinc, and 



286 GALVANIZING AND TINNING 

by extending the time of the operation or increasing the tempera- 
ture, same will be reduced very rapidly until about 20 per cent, 
metallic, at which time it should be disposed of. There is always 
a market for this material, providing no sands, flint or other ma- 
terials are mixed with the zinc for coloring purposes. This has 
been one of the objectionable features in the process, and very de- 
ceiving to the public in giving color and not zinc simply for 
appearance. 



CHAPTER XXXII 

Galvanizing Specifications and Tests 

THE following specifications applied to the galvanized over- 
head construction material purchased by the Pennsylvania 
Eailroad for the Philadelphia electrification, and all gal- 
vanized material used by the New York, New Haven & Hartford 
Railroad in their electrification improvements was required to meet 
these specifications before being accepted. 

Specifications for Hot and Electro -Galvanizing 

This specification shall apply to all galvanized iron or steel ex- 
cept that coated with zinc by the Sherardizing process. 

Coating 

The galvanizing shall consist of a continuous coating of pure 
zinc of uniform thickness, and so applied that it adheres firmly 
to the metal. The finished product shall be smooth. 

Cleaning 

The samples shall be cleaned before testing, first with carbona, 
benzine or turpentine, and cotton waste (not with a brush), and 
then thoroughly rinsed in clean water and Mdped dry with clean 
cotton waste. 

Solution for Testing Coating 

The standard solution of copper sulphate to be used in testing 
shall consist of commercial copper sulphate crystals dissolved in 
cold water, about in the proportion of thirty-six parts, by weight, 
of crystals to 100 parts, by weight, of water. The solution shall 
be neutralized by the addition of an excess of chemically pure 
cupric oxide (CuO). The presence of an excess of cupric oxide 
will be shown l)y the sediment of this reagent at the bottom of the 
containing vessel. 

The neutralized solution shall be filtered before using by pass- 
ing through filter paper. The filtered solution shall have a specific 
gravity of 1.186 at 65 deg. Fahr. (reading the scale at the level of 

287 



288 GALVANIZING AND TINNING 

the solution) at the beginning of each test. In case the filtered 
solution is high in specific gravity, clean water shall be added to 
reduce the specific gravity to 1.186 at 65 deg. Fahr. In case the 
filtered solution is low in specific gravity, filtered solution of a 
higher specific gravity shall be added to make the specific gravity 
1.186 at 65 deg. Fahr. 

As soon as the stronger solution is taken from the vessel con- 
taining the unfiltered neutralized stock solution, additional crys- 
tals and water must be added to the stock solution. An excess of 
cupric oxide shall always be kept in the unfiltered stock solution. 

Quantity of Solution 

Wire samples shall be tested in a glass jar of at least two inches 
(2 in.) inside diameter. The jar without the wire samples shall 
be filled with standard solution to a depth of at least four inches 
(4 in.). Hardware samples shall be tested in a glass or earthen- 
ware jar containing at least one-half (i/^) pint of standard solu- 
tion for each hardware sample. 

Solution shall not be used for more than one series of four im- 
mersions. 

Samples 

Not more than seven wires shall be simultaneously immersed, 
and not more than one sample of galvanized material other than 
wire shall be immersed in the specified quantity of solution. 

The samples shall not be grouped or twisted together, but shall 
be well separated so as to permit the action of the solution to be 
uniform upon all immersed portions of the samples. 

Tests 

Clean and dry samples shall be immersed in the required quan- 
tity of standard solution in accordance with the following cycle 
of immersions. 

The temperature of the solution shall be maintained between 
63 and 68 deg. Fahr. at all times during the following te!st : 
First. Immerse for one minute, wash and wipe dry. 
Second. Immerse for one minute, wash and wipe dry. 
Third. Immerse for one minute, wash and wipe dry. 
Fourth. Immerse for one minute, wash and wipe dry. 
After each immersion the samples shall be immediately washed 



GALVANIZING SPECIFICATIONS AND TESTS 289 

in clean water having a temperature between 62 and G8 deg. Fahr., 
and wiped dry with cotton waste. 

In the case of No. 14 galvanized iron or steel wire, the time of 
the fourth immersion sliall be reduced to one-half minute. 

Results of Tests^ 

After the tests described in "Tests" alcove, no bright metallic 
copper deposit shall show on the samples. 

In case the article is threaded, the thread shall be clean and true 
after galvanizing and shall stand at least one immersion in the 
test solution. The rest of the article shall stand the specified four 
immersions. 

The threads of nuts, except those galvanized by the electrolytic 
process, shall be cut after galvanizing, and the threads shall not 
be required to pass the tests. 

Copper deposits on zinc, or Avithin one inch of a cut end, shall 
not be considered causes for rejection. 

In case of failure of only one wire in a group of seven wires 
immersed together, or if there is a reasonable doubt as to the 
copper deposit, two check tests shall be made on these seven wires 
and the lot reported in accordance with the majority of the sets 
of tests. 

Failure to Meet Requirements 

Any shipment or part of a shipment, the samples from which 
fail to pass the above requirements, may be rejected. 

Testing Galvanized Products 

Obviously the only final durability test of a zinc coating is the 
test of time while in use under actual conditions of exposure. 
This method however takes too long for commercial purposes and 
some other means of making comparative tests Avhich will give 
prompt results must be adopted. Several such tests are in general 
use, and the following information taken from a booklet entitled 
"The History and Development of the Galvanizing Industry" and 
reprinted in Metal Indusfrij covers the subject in an interesting 
manner : 

Tlie outward appearance of any galvanized article is not neces- 
sarily an indication of its excellence. This statement may be 
taken as a general rule applying to articles coated by either of the 
galvanizing processes mentioned herein. 



290 GALVANIZING AND TINNING 

For over forty years prior to 1880 the hot galvanizing process, 
Avhich was practically the only galvanizing process in commercial 
use prior to that time, was believed to produce uniform results. 
It was, therefore, not deemed necessary to test such coatings by 
any other means than that of durability under actual weather con- 
ditions. Observations made by Sir W. H. Preece, chief of the 
British Post Office Telegraphs, led him to see the necessity of a 
test for zinc coatings on telegraph wires. 

Preece, or Copper Sulphate Test 

Between 1880 and 1890 Preece devised what is known as the 
"copper sulphate test" for galvanized articles, and this test has 
until recently been accepted as the final word regarding the quant- 
ity of any galvanized product. This test has been modified and 
standardized in the United States^ notably by the chief engineer 
of the Western Union Telegraph Company, and has been quite 
generally adopted by producers and consumers of galvanized prod- 
ucts, such as wire, sheets, line material, etc. 

The original Preece test consisted in the immersion of the gal- 
vanized article in a saturated solution of coj^per sulphate for a 
period of one minute, removing, rinsing in water, wiping and 
again immersing in the copper sulphate solution. The number 
of immersions which the article could withstand before showing 
bright copper on the underlying steel or iron was taken as an 
indication of the excellence of the zinc coating. 

Temperature Important 

As at present standardized careful preparation of the copper 
sulphate solution is necessary. The solution is brought to a den- 
sity of 1.186 specific gravity at a temperature of 65 clegs. Fahr. 
This solution is usually treated with a small portion of cupric 
oxide to neutralize any free acid which might exist in the copper 
sulphate crystals. Galvanized articles are first to be cleaned of 
dirt and grease by immersion in gasoline or benzine, then rinsed 
in water and wiped dry. 

After this preparatory treatment the articles are given succes- 
sive one-minute immersions in the standard copper sulphate liquor, 
held at a temperature of from 65 to 70 degs. Fahr., rinsed thor- 
oughly in water and wiped dry after each immersion. The samples 
are to be carefully scrutinized after each immersion, and if spots 



GALVANIZING SPECIFICATIONS AND TESTS 291 

of a clear copper color are observed, the coating is said to have 
failed. The number of successive immersions which the article 
will withstand without sliowing indications of clear copper is 
taken as an indication of the quality of the coating. A new por- 
tion of solution is to be taken for testing each article. 

Limitations of Copper Sulphate Test 

It will be noted that the Preece, or copper sulphate test, de- 
termines onlv^ the thickness of the zinc coating at its thinnest por- 
tion. It is, therefore, not in any sense a determination of how 
much or how little zinc is deposited on the article under test. It 
is well known that the copper sulphate test is unsuitable for test- 
ing Sherardized articles, and it is a fact, however not generally 
known, that the copper sulphate does not attack zinc coatings 
deposited electrically, and by hot galvanizing methods at equal 
rates. It has been further demonstrated that the different tem- 
peratures of the molten l)ath and different methods of cooling 
articles galvanized in molten zinc show entirely unreliable results 
when subjected to the copper sulphate test. From these remarks 
it will be seen that it is unfair to test competitively zinc coatings 
applied by Sherardizing, hot galvanizing and electro-galvanizing 
methods. 

Lead Acetate Test 

Owing to the unsatisfactory results secured by means of the 
copper sulphate test, in a measure pointed out in the preceding 
paragraphs, an accurate quantitative test for galvanized ^^roducts 
has been devised. The lead acetate test, as it is known, was re- 
cently originated by Prof. W. H. Walker, of the Massachusetts 
Institute of Technology, Boston. 

The test is designed to show the weight of actual coating cov- 
ering products galvanized by any of the well-known methods. It 
takes into consideration the impurities residing in the coating and 
the main impurity usually found, i. e., iron, may be determined 
if desired. In practice, however, it is seldom carried out to this 
extent. The solution employed removes from the articles both the 
zinc and zinc-iron alloys present. The accurate weight before and 
after testing furnishes the basis for computing the quantitative 
value of the coating. It is unnecessary to take the time of sample 
immersion accurately, in which respect the lead acetate test differs 



292 GALVANIZING AND TINNING 

from the coiDper sulphate test ; hoAvever, the weighings, which must 
be accurate to one milligram, require considerable time and care. 
The lead acetate solution is prepared as follows: 

Dissolve 3 pounds of commercial lead acetate crystals 
(Pb (C2H302)3-|-3H„0) in one gallon of distilled water and add 
1 oz. litharge (PbO). After complete solution of the lead acetate, 
tJie mixture should l)e stirred vigorously and any undissolved resi- 
due allowed to settle. The clear liquor is then poured off and the 
solution is ready for use. It is unnecessary to maintain any ac- 
curate temperature of solution as is required in the copper sulphate 
test, and the solution may be used for several tests without renewal, 
until such time as the action becomes too slow. 

Samples of galvanized product are first to be thoroughly cleaned 
of oil and dirt by rinsing in benzine or in gasoline, then rinsing in 
cold water and dried with clean cotton waste. The sample should 
next be weighed to an accuracy of one milligram, and the weight 
noted. The samj^le is then ready for immersion in the lead acetate 
solution. 

The length of time during which the sample is under treatment 
is usually aljout three minutes, althougli it may be left in for a 
longer jjeriod without affecting the result. These immersions should 
be repeated until all of the coating has been removed and the 
sample exhibits the clean steel underneath. A short experience will 
enable the operator to tell with certainty when all of the coating 
has been removed. After each immersion in the lead acetate solu- 
tion, the fiocculent or loose coating of spongy lead which is de- 
posited must be carefully removed ; for this purpose it is usual to 
employ a small, soft l)ristle brush, care being taken that no lead 
is 'H^urnished" over the zinc coating. If any spots of lead are 
noted, which the solution does not remove, the careful use of a 
sharp knife is necessary. When the coating is all removed, the 
sample is then dried by immersion in alcohol and ignition, or by 
placing over a small steam coil. Final weight of the sample is then 
taken and noted. 

If it is desired to estimate the amount of iron in the coating, 
the samples must be rinsed in clean water contained in a beaker, 
care being taken that all lead acetate and solution washings are 
saved. The lead acetate and the wash solutions may be put to- 
gether and filtered, and slightly acidified with sulphuric acid ; a 
few particles of granulated zinc should then be added, when the 



GALVANIZING SPECIFICATIONS AND TESTS 293 

amount of iron is ascertained l)y titrating the solution with a 
standard solution of pota.ssiuni-pernianganate. The lead may be 
hailed and squeezed with the fingers, and saved if desired. 

The lead may be weighed and the amount of zinc coating re- 
moved may be calculated from the weight of the lead, the preferable 
manner of determining the amount of coating on the sample under 
test is as follows: Deduct the final Aveight of sample after treat- 
ment in the lead acetate solution from the original weight of the 
galvanized piece. Divide tlie net weight of coating so obtained by 
the weight of the bare or uncoated sample, whence the per cent, of 
loss in weight is ascertained nearly eiiough for all practical pur- 
poses. Apply the per cent, loss figure to 2,000 lbs. representing a 
ton of the articles in question. This will give the pounds of coat- 
ing per ton of product. 

Next, ascertain by close measurement or estimation how many 
sq. ft. of surface there are in a ton of 2,000 lbs. of the articles 
under examination, reducing the lbs. coating per ton found by the 
application of the percentage figure, to ounces by multiplying by 
16. Having the ounces of coating per ton and tlie numl^er of sq. 
ft. of surface per ton, divide the former figure by the latter, and 
find the ounces per sq. ft. ; this is usually a decimal figure. The 
ounces of coating per sq. ft. gives a unit which may be used for the 
purpose of comparing the values of coating on different styles and 
kinds of galvanized product. 

Samples of galvanized articles which are to be given the lead 
acetate test must he above all things smoothly galvanized, without 
adJiering lumps or drops of spelter, since these imperfections would 
lead to erroneous conclusions by adding to the net weight of coating 
particles of metal not evenly distributed, wherefore the resultant 
ounces per sq. ft. would be too high ; it should be carefully observed 
that all portions of the galvanized article are coated, unless the un- 
coated areas are left out of the area figure per ton. 

Caustic Soda Test 

Prof. Walker has rendered further service to those interested in 
testing galvanized materials by supplying a test which will show 
the presence or absence of pores or cracks in zinc coatings. 

A strong solution of caustic soda in water is heated to a tempera- 
ture of about 210 degs. Fahr., and the galvanized article suspended 
in this solution by a string or other non-metallic suspension. If 



294 GALVANIZING AND TINNING 

pin holes or cracks exist in the coating, bubbles or hydrogen will be 
ol}served to come from the surface of the article at these points, 
while if there are no pores or cracks in the coating, no action will 
be observed. The caustic soda test will show whether or not the 
coating has cracked when the galvanized article is bent after gal- 
vanizing. 

In a recent issue of The Iron Age Mr. Samuel Trood has also 
given special consideration to the use of the various texts from the 
standpoint of an expert on Sherardizing. 

The Preece Test 

The solution is made up by dissolving 36 parts by weight of 
commercial copper sulphate crystals in 100 parts of water and then 
neutralizing by the addition of excess of chemically pure cupric 
oxide. The presence of excess oxide is indicated by the undissolved 
part settling to the bottom of the vessel. 

It is difficult and takes much time to get the copper sulphate into 
solution at room temperature, even if the solution is agitated by 
blowing air tlirough it, or if the crystals are suspended in a basket 
near the top of the solution. Heating will greatly accelerate the 
rate of solution, and in this way a solution can be prepared a little 
stronger than that desired, the final exact adjustment being after- 
ward made by diluting with water. To do this accurately and rap- 
idly, add a certain number of cubic centimeters of water to about 5 
liters of solution, and note how many thousandths change this pro- 
duces in the specific gravity. One or two further additions will 
then suffice to get an accurate adjustment of the strength. 

It was noted that, after the finished solution has been filtered 
olf from the copper oxide, CuO, in the bottom of the stock bottle, 
there is separated out, sometimes a reddish or sometimes a bulky 
pale green precipitate, after the solution has stood for a consider- 
able time, due to some impurity, or it may be to some basic salt of 
copper. It probably does not affect the strength or neutrality of 
the solution appreciabty, since the quantity is not great. How- 
ever, for very accurate work it might be desirable to determine the 
effect of this change, and whether it is desirable to always use a 
solution recently filtered off from CuO sediment. 

The descriptions of the test specify that the strength of the solu- 
tion shall be 1.186 at 65 deg. Fahr. It would be desirable to know 
the permissible variation from this, that is, the error due to having 



GALVANIZING SPECIFICATIONS AND TESTS 20^. 

the streno-tli 1.181 or 1.188, for example; furtlier, it would simplif}' 
tlie operation ol' making up the solution, if only an occasional one 
is made up and means for getting the temperature exactly adjusted 
are not convenient, to know what specific gravity to aim for if the 
temperature is 70 deg. or 80 deg. Fahr. After the strength has once 
been adjusted, the temperature at which the solution is used has an 
effect upon the accuracy of the test. This will be taken up in an- 
other paragraph. 

Manipulation of the Test 

There does not seem to be published information on the one 
point that determines whether or not the 023erator will have suc- 
cess when he attempts to apply the Preece test to Sherardized and 
alloy-coated articles. This is that the specimen must be brushed 
instead of wiped, in removing the loose copper after each dip. 

The copper wliich replaces the zinc on a galvanized coating is in 
such a loose non-adherent form that it can be easily wiped off with 
cotton w^aste, but that which forms on Sherardized coatings is more 
adherent, probably due to the slower rate at which zinc-iron alloy 
precipitates copper from the solution as compared with zinc itself. 
FurtJier, the Sherardized surface is rough so that, if the specimen 
is wiped with waste, the copper, instead of being removed, is rubbed 
into the hollows of the surface. This copper then protects the still 
remaining underlying alloy from further action of the solution and 
the test is .spoiled. The further solution of the protected alloy is 
retarded so that, if the dips are continued, the specimen will appear 
to stand more dips than correspond to the thickness of coating 
present or even may stand an indefinite number of dips. On the 
other hand, if the operator has not had some experience, he may 
interpret this premature appearance of copper as a failure, since 
after several burnishings by waste, the copper on alloy may take a 
polish that resembles closely the appearance of copper formed on the 
iron. By removing the cop^Der after each dip by vigorous brush- 
ing with plenty of water, as under a faucet, the risk of rubbing it 
into the hollows is practically eliminated. 

In a Sherardized specimen the portion of the coating next to 
the iron shows a lighter color during the Preece test than that 
nearer the surface. For this reason, then, after brushing and dry- 
ing, a light patch shows up on a darker background, it indicates that 
the coating is thin at that point and failure is to be expected. 



296 GALVANIZING AND TINNING 

Sometimes, due to imperfect brushing, copper will form on the 
surface of the coating, as mentioned, but this copper can be dis- 
tinguished from the copper formed on the iron at the point of 
failure in several ways. The copper at the failure is lighter in 
color than that due to improper brushing, it is surrounded by an 
area of light colored coating and it forms in the hollows or 
"valleys" of the coating, while the other forms on the higher por- 
tions or "hill tops." This last difference is always noticeable under 
a magnifying glass, but it can be distinguished by the eye after a 
little practice. 

The regular Preece test was made on some No. 16 gauge wire 
which had been given a Sherardized coat in such a manner that it 
was very smooth. It was noticed that the copper which formed 
could be wiped off with waste and that the test would give the same 
results whether the wiping was done by waste or by brush. In 
order to determine whetlier the character of the coat affected this, 
similar tests were made on Sherardized sheet. One sheet had a 
rough coat while the other was smooth. Both were dipped at the 
same time in the same solution and both were wiped with waste. 
After the fourth dip the copper which had deposited on the rough 
specimen was rubbed into the crevices of the surface and gave a 
copperish color to the specimen. Large patches of this copper were 
burnished to a metallic polish. The copper which had deposited 
on the smooth piece showed practically no tendency to remain, as 
there were, few cracks or hollows in which it could form. 

A specimen of Sherardized sheet "Zy^^i in., with a very thick 
Sherardized coating, was dipped info a solution 2 inches. One-half 
of the tested part was brushed after each dip and the other half 
was wiped with waste. After the third dip line copper began to 
collect on the wiped half in the crevices of the coat and the amount 
increased after each dip. The brushed side kept a uniform dark 
color through the entire test showing no deposition of copper. The 
copper formed on the wiped half became thicker after each dip. 
The Sherardized coating where it was not protected by this layer 
of copper became thinner and eventually failed. The appearance 
of the coating on the brushed half was uniform and showed no in- 
dication of failure. The elevated deposit of copper on the wiped 
half could be flaked off. The premature failure of the wiped half 
was due to the accelerating action of the heavy elevated deposit of 
copper; that is to say, the burnished copper on the alloy protects 



GALVANIZING SPECIFICATIONS AND TESTS 297 

only tlie alloy (lii'octly lioiicatli it, l)ut acecloratcs tlic solution of 
immediately adjoin iiii;- areas of alloy. The elevated copper had a 
nodular rough surface wliile that deposited on the iron at the 
failure was smooth and bright. 

Temperature of the Solution 

The American Steel & Wire Company specifies that in carrying 
out the dip test the temperature of the solution must be between 
05 and 70 deg. Fahr., while the American Telephone & Telegraph 
Company specifies 02 to 68 deg. Falir. It is of interest to know the 
percentage of error due to temperature variations, especially when 
only an occasional test has to be made, since it may then take much 
more time to arrange to get the right temperature than to run the 
tests. Results ol)tained with solution at different temperatures, 
75 c.c. of solution being used, are : 

Average loss, 
Tempoiature gr. per sq. in. 

55 deg. F 0.0291 

65 deg. F 0.03185 

75 deg. F 0.0345 

85 deg. F 0.0397 

These figures show that if a specimen is very close to the point 
of rejection a difference of 10 degrees may easily mean rejection or 
acceptance for the same actual thickness of coating. 

Consideration of Objections to Preece Test 

The accuracy of the Preece test has been called into question by 
Patrick and Walker (Journal of Industrial and Engineering Chem- 
istry, April, 1911), for the reason that the rate at which CuSO^ 
solution dissolves zinc is different from the rate of solution for 
7inc-iron alloy. The rate of solution is slower for the zinc-iron 
alloy because of its lower potential as compared with zinc. But this 
lower potential would seem to indicate a correspondingly slower 
corrosion by atmospheric influence, so that the number of dips in 
a corrosive solution tliat a specimen will stand is a fairer indica- 
tion of its resistance to corrosion, and tlierefore the usefulness of 
the coating, than the actual weight of the zinc present. It is a 
determined fact that less weight of zinc in the form of Sherardized 
coat will afford protection equal to a greater amount of zinc in the 
form of a hot or electrogalvanized coating. 

Determinations have been made of the relative rate of solution 



298 GALVANIZING AND TINNING 

of several kinds of coating in tlie standard CuSO^ solution with the 

following- results : 

Loss, gr. per 
Specimen sq. in. per dip 

Hot galvanized wire 0.0135 

Alloy coated nail (Sherardized) 0.0082 

Sherard-jct 0.0109 

Gaivaduct 0.0131 

It is evident that the Sherardized coat dissolves materially more 
slowly. 

In comparing one specimen of hot galvanized material with an- 
other, there may be a slight discrepancy in the relation between 
the number of dips and the actual weight of coating. This is due 
to the fact that in different specimens of hot galvanizing the ratio 
between alloy and pure zinc present may vary from something like 
1 of alloy to 4 of zinc, to 1 of alloy to 10 of zinc. Again, it may 
be fairly assumed that the important thing to know is the number 
of dips the specimen will stand rather than the weight of material 
present. If, however, some buyer or manufacturer should consider 
weight the only factor of importance, it is evident that a difference 
of rate, as indicated in the above table, is not so serious when it is 
borne in mind that it affects only 14 to 1/10 of the coating; 
further, when the Preece test is used as a regular commercial con- 
trol by some buyer or manufacturer, the articles compared from 
day to day are probably usually so made that the variation in the 
proportion of alloy present is not a maximum one. 

In the same article, Patrick and Walker assert that the end point 
is unreliable. x\s far as Sherardized articles are concerned, prac- 
tically all of this uncertainty as to the end point arises from the 
fact that the specimen is not brushed properly. The importance 
of this has been discussed under "Manipulation of the Test." It is 
true, however, that it takes more practice and more careful dis- 
crimination to" use the Preece test for Sherardized articles than for 
hot or electrogalvanized objects. 

In order to get additional proof that really adherent copper de- 
posits only upon iron and not upon alloy, specimens were prepared 
and examined under the microscope. It was noted that the only bright 
copper oil the brushed specimen was on the iron, Avhile the thin 
alloy surrounding the place of failure showed none whatever. Be- 
fore brushing there was copper on this alloy. 

Sellers of hot galvanized ware have raised objection to permitting 



GALVANIZING SPECIFICATIONS AND TESTS 299 

the brushing- of samples of Sherardized ware, in carrying out the 
Preece test. As long as there is any coating left the brushing can 
certainly do notliing that would make the Sherardized article show 
up better than it should ; if anything it would, remove some of the 
coating and hasten the failure, to which the sellers of galvanized 
ware would certainly not object. 

The only possible contentions of the hot galvanized ware sellers 
would then be that the brushing might remove copper that is de- 
posited upon iron. According to observations made on this point, 
only the most violent brushing will do this and there is not the 
slightest difficulty in avoiding it. The use of the stiffest brush 
that could be bought in a local drug store did not bring about the 
removal of this copper, and a much softer brush is perfectly suffi- 
cient to give the samples all the brushing they need, if only a 
burnishing effect is avoided. 

Probably the only way in which there is danger of removing 
copper from iron is a bending back and forth or other considerable 
distortion of the specimen; or, after the coating has been removed 
and the next dip would deposit copper and iron, to get the specimen 
dirty or greasy by using a greasy or soapy brush or handling with 
the hands. If the sample is laid upon a board, in brushing, as may 
be desirable with light flexible objects, in order not to scale off any 
copper, the board should of course be free from soap, grease, dirt 
or chemicals. 

The Lead Acetate Test 

In preparing the solution used, difficulty was found in getting 
the prepared quantity of lead acetate into solution. It is true that 
by heating this solution would be indicated. One difficulty en- 
countered in working the test was due to the deposition of adherent 
lead on Sherardized samples immediately on immersing, particularly 
those coated by dust. This adherent lead cannot be wiped off and 
protects the underlying coating from going into solution. The 
area of adherent lead on some specimens was over 90 per cent, of 
the total surface. 

Before the remedy for obviating the formation of adherent lead 
had been found, it was attempted to determine the loss of weight 
per dip. Instead of a loss, a gain in weight was found, showing con- 
clusively that adherent lead was formed. Test pieces consisting of 
Sherardized nails with the points cut off were used. These were 



300 GALVANIZING AND TINNING 

immersed each time to constant depth. The area of the surface ex- 
posed was therefore constant in each dip. The nails were cleaned 
in gasoline, washed and dried; one-minute dips; brushed lightly and 
dried after each dij). 

During Nail No. 1, Nail No. 2, 

dip No. gain in grams gain in grams 

1 0.0011 0.0014 

2 0.0024 0.0020 

3 0.0028 0.0014 

4 0.0010 0.0003 

A similar nail was dipped into the solution and only adherent 
lead formed. The nail was removed and a knife blade scraped 
lightly across the surface and replaced. Loose, Idack crystalline 
lead immediately formed on the scratched portion, while none 
formed on the other parts of the nail. 

Two nails similar to those previously mentioned were dipped in 
the same manner after they had been l)rushed with a dry brush and 
wiped with, a dry towel. The deposition of loose lead in this case 
took place in spots, but covering the lesser part of the surface. 
These spots grew sloAvly during the dip. The brushing after each 
dip was done lightly. 

During Nail No. 1, Nail No. 2, 

dip No. loss in grams loss in grams 

1 0.0008 0.0036 

2 0.0018 0.0029 

3 0.0017 0.0051 

As will 1)0 seen from the next determination, these are not 
normal results. ^Several other devices were tried to bring about 
the proper action of the solution. The specimens were thoroughly 
moistened, a hot solution was tried, the specimens were moved 
around in the solution, but no results were obtained. 

In the next test the sample was treated before dipping with about 
20 per cent, acetic acid for al)out 20 seconds, or until a distinct 
evolution of gas took place over its entire surface. After washing 
and drying it was dipped and weighed as in the previous test. The 
deposition of loose lead took place over the entire surface im- 
mediately after immersion. 

Nail No. 3, 
During Nail No. 3, Loss grams 

dip No. Loss in grams per sq. in. 

1 0.0201 0.0199 

2 0.0163 0.0161 

3 0.0138 0.0137 

4 0.0141 0.0140 



GALVANIZING SPECIFICATIONS AND TESTS 301 

A similar test witli a larger nail, dipped in acetic acid before 
putting into the lead acetate solution, gave the following results: 

, Nail No. 4 , 

During Loss grams 

dip No. Loss in grams per sq. in. 

1 0.0120 0.02.35 

2 0.0084 0.016.5 

;^ 0.008.') 0.0167 

4 0.0002 0.0180 

5 0.0089 0.0174 

6 0.0086 0.0169 

Instead of dilute acetic acid, very dilute hydrochloric acid can 
also be used, about 10 per cent., and the specimen immersed in this 
about 10 seconds. It is probable that the reason that the lead 
acetate solution does not act properly at the start is that there is 
some zinc or iron oxide on the surface of the object. 

Patrick and Walker do not approve of a "dip" method of 
testing the thickness of a coating, no matter Avhat solution is used, 
but believe that the veight of the coating should be determined, 
either by weighing the kad deposit or by noting the loss of weight 
of the specimen. Either of these methods takes more time than 
that of counting dips, and the method of collecting, drying and 
weighing the lead seems especially cumbersome for a routine works 
test. The calculation of the results will take time also, unless 
there are a great numl^er of samples of the same shape and size to 
l)e tested. 

Preece and Acetate Methods Compared 

1. For commercial testing the Preece method can be satisfac- 
torily used for Sherardized as well as for hot dip and electrogalvan- 
ized articles, if the specimens are brushed properly. It takes more 
practice to detect the end point for testing Sherardized goods. 

2. When used as a dip method the lead acetate test has the ad- 
vantage of showing the end point with less practice on the part of 
the operator. It is troublesome for Sherardized articles since the 
samples must be dipped in acid, as described, in order that the test 
can be worked. 

3. The lead acetate solution removes about 1.6 times as much 
coating per dip as the copper sulphate solution. It would be de- 
sirable, in order to prevent confusion, to adjust the solution, if 
possible, so that a dip removes the same quantity in both cases. If 
a weaker solution is used in order to reduce the rate of solution 



302 GALVANIZING AND TINNING 

for tlie lead acetate solution there may be more trouble with the 
formation of adherent lead. 

4. As a testing method for scientific investigations to determine 
the exact weight of coating the lead acetate determination has the 
advantage that it removes the coating without depositing anything 
on the iron, resulting in an accurate determination. However the 
error due to the small amount of copper replacing iron cannot 
be material if it is desired to use the copper sulphate solution in 
order to determine the loss of weight of the specimen. 

5. The lead acetate method affords a means of determining the 
percentage of iron in the coating. This is not essential for routine 
factory testing, and in fact the iron determination would be too 
troublesome for regular works control. 

6. If it does not seem possible or desirable to overcome the ob- 
jections of the sellers of hot galvanized ware to brushing Sher- 
ardized samples during the Preece test, the lead acetate method 
may be a useful substitute or at any rate a good check method to 
show that l)riishing does not result in too favorable indications for 
Sherardized goods when tested by the Preece method. 

7. It does not seem justifial)le to concur in Patrick and Walk- 
er's recommendation to substitute a weighing method for the dip 
method for commercial purposes, or to substitute the lead acetate 
dip method for the copper sulphate method. 

Electrolytic Methods 

Some experimental work was carried on which showed that by 
removing a Sherardized coating by electrolysis in a solution of 
potassium nitrate the ampere-minutes of current passed would indi- 
cate the weight of the coating. At this time the tests were all 
carried to the point of total removal of the coating. 

If this method were modified, so that a constant amperage were 
used, and the specimen removed from the solution from time to 
time, say every half minute, and the test stopped when failure was 
first noted, the thickness of coating would be indicated by ampere 
minutes, which in this case could be readily noted since the am- 
perage has been kept constant. In order to insure a uniform rate 
of solution for all parts of the sample, all parts of the specimen 
should be equally distant from the cathode. If the shape of the 
object prevents this, the distance should be made great enough, by 
using a large vessel, so as to make the variations insignificant. 



GALVANIZING SPECIFICATIONS AND TESTS 303 

Care must l)e taken to use a voltage lower than the decomposition 
voltage of water. 

As regards the Shcrardizcd coating, the disadvantage of this 
method would be that the same or greater weight of coating would 
go into solution per ampere minute as for hot galvanized. As 
pointed out, this is not the ease with the Preece test. However, 
the test might at times ))e useful for a laljoratory test for the use 
of the Northern Chemical Engineering Laboratories, or as a check 
method, without making any effort to bring about its general adop- 
tion as a commercial control method. 

Caustic Soda Test 

Another test for a zinc coating is the caustic soda test as supplied 
by Professor Walker. This test will show the presence or absence 
of pores or cracks in zinc coatings. The galvanized article is sus- 
jiended by a string or other non-metallic suspension in a strong 
solution of caustic soda in water, heated to a temperature of 210 
dgs. Fahr. If pin holes or cracks exist in the surface, bubbles of 
hydrogen Avill be observed to come from the surface of the article 
at these points, while if no pores exist no hydrogen will be evolved. 

After considering all the possible methods of testing protective 
coatings, Avhich is the best method for testing Sherardized material ? 
The best one is that which can be successfully used on a commercial 
scale by a $13 a week apprentice 

Government Galvanizing Test 

In using this test, take distilled water and sulphate of copper, 
C.P., sufficient to make a saturated solution leaving some sulphate 
undissolved. Solutions to be used at a temperature of 60 deg Fahr. 
Test calls for one minute immersion of galvanized work, after which 
the work is rinsed in cold water and dried, and again immersed 
in a new testing solution for one minute and again washed and 
dried out and so on until the requisite number of one-minute dips 
have l)een made. When the zinc coating breaks down and shows a 
deposit of bright coppery red the test is finished. A slight appear- 
ance of copper does not necessarily mean that the zinc; coating is 
entirely broken down, but, a bright red deposit must show. For 
some characters of work two one-minute tests are required without 
the galvanized coating l^reaking down, in others four are required. 

Professor Burgess, of the University of AVisconsin, who has com- 



304 GALVANIZING AND TINNING 

piled very interesting data, some of which has been quoted, has 
found that this test is not always suitable for judging the thickness 
and quality of electro-zincing. For testing the power of resistance 
of the coating Professor Burgess -has made use of diluted sulphuric 
acid and has found that an electrically deposited coating one-third 
the weight of that produced by the hot galvanizing processes has 
the same power of resistance to corrosion as the latter and that for 
a coatmg of equal thickness the proportion of resisting power is 
as 10 :1, ' 

A table showing the time of deposit, current used in number of 
amperes and the resistance to successive one-minute immersions as 
indicated in government test is appended. 



Amperes used 


1 st test 


2nd test 


2rd test 


4tli test 


per sq. ft. 


Ve oz. 


1/3 oz. 


1/2 oz. 


% oz. 


surface 


per sq. ft. 


per sq. ft. 


per sq. ft. 


per sq. ft. 




Minutes 


Minutes 


Minutes 


Minutes 


100 


2% 


5 


7% 


10 


90 


2% 


5% 


8 


11 


80 


3 


6 


9 


12 


70 


3% 


7 


101/3 


14 


60 


4 


8 


12 


16 


50 


5 


10 


15 


20 


45 


51/2 


11 


16% 


22 


40 


6 


121/2 


19 


25 


35 


7 


14 


21 


28 


30 


8 


I6V2 


25 


33 


25 


10 


20 


30 


40 


20 


121/0 


25 


37% 


50 


15 


101/2 


33 


50 


66 


10 


25 


50 


75 


100 



Salt Spray Test for Sherardizing 

Another test which is claimed to be jjarticularly well adapted to 
making comparisons of the durability of metallic coatings applied 
by processes of different character is described in a paper read by 
Mr. J. A. Capp, of tlie General Electric Company, at the seven- 
teenth annual meeting of the American Society for Testing Ma- 
terials. 

There are several processes commercially used for covering the 
surfaces of metals easily corroded or rusted, such as iron in its 
several forms, with other metals less easily corroded, or with 
metallic oxides. These may well be called "metallic" protective 
coatings in distinction from the types of coating which are in the 
nature of paints or their equivalent. 

The object of the application of these metallic protective coatings 



GALVANIZING SPECIFICATIONS AND TESTS 305 

is to enable the coated articles to resist atmospheric exposure with- 
out rusting for a longer time than they could withstand such ex- 
posure without protection. Obviously, then^ the only final test of 
the efficiency of a given type of coating is actual exposure to the 
same sort of influences that the material is supposed to resist in 
service. If the coating is at all efficient, this takes so long a time 
that more rapid methods of determining relative efficiencies be- 
come a necessity. The most commonly used methods 'of testing 
such metallic protective coatings are those of chemical attack, which 
in effect measure either the thickness or the weight per square unit 
of the protective coating. Such methods of chemical attack permit 
the comparison of results obtained from tests upon the same sort 
of coating, but difficulty is encountered when attempt is made to 
compare the results obtained by such tests on one sort of coating 
with those obtained on another character of coating. For instance, 
the well-known Preece test yields excellent comparative results on 
galvanized coatings. When, however, it is used for coatings ap- 
plied by the Sherardizing process, the results are not at all com- 
parable. ISTeither is the Preece test applicable to coatings of tin or 
of lead. In the case of Sherardized articles, it has been suggested 
that the coat, Avhich is a combined structure of zinc and zinc oxide, 
together with some zinc-iron alloy, be removed m strong alkalies 
which will not attack the iron beneath. This would enable one to 
determine the weight of coating per unit of surface calculated to 
metallic zinc, but experience has shown that the results do not 
necessarily indicate the efficiency of the coat, and that it is not 
easy to determine the relative proportions of zinc and zinc oxide. 
Furthermore, comparison of the efficiency of a Sherardized coating 
with ordinary galvanizing is not possible when the Sherardized 
coating is tested by solution in a caustic alkali, while the galvanized 
coating is subjected to the Preece test. 

Some years ago, when testing electrical insulation such as is 
used for overhead line construction, we found that material which 
stood fairly well when immersed in water failed badly when ex- 
posed to the weather, especially if exposed during a hard rain. 
This led us to produce a rain in the laboratory by sending a stream 
of water through an ordinary rosette such as is used with a garden- 
er's watering can. The results were encouraging, but too severe, 
because the individual streams played steadily on one spot and 
produced erosion. Then we tried an atomizing nozzle, projecting 



306 GALVANIZING AND TINNING 

a cloud of moisture into a chamber in which the test specimens were 
exposed; the results were better, but there was still a possibility 
of some wear if the article was directly in the path of the stream 
and near to the nozzle. The problem seemed to be solved when 
care was taken in placing the articles to keep them out of the 
direct path of the jet issuing from the atomizing nozzle. As ex- 
perience was gained with this type of test, as applied to insulating 
material, it was found that what seemed to be the essential re- 
quirement was the maintaining of an atmosphere substantially 
saturated with moisture; and this saturated-atmosphere exposure 
has been one of the tests regularly applied to all insulating ma- 
terials intended for outdoor use since it was first worked out some 
fifteen years ago. It has been found to give reliable indications 
of the alulity of insulation to resist weather, except, of course, as 
such ability is afl'ected by extremes of heat and cold, erosion from 
the wind carrying dust particles, etc. 

The problem of determining the resistance of protective coatings 
to weather corrosion is very similar to that of testing insulations 
for their weathering qualities. The conditions of exposure are the 
same, and hence there seemed to be no essential reason why the 
saturated-atmosphere test would not apply equally well to pro- 
tective coatings as to insulation. Tests were begun several years 
ago to try out the method, and the only fault found with it was 
th.at it was somewhat slow. Good coatings did not show any signs 
of breaking down after several weeks of continuous exposure to 
the fog; yet there was encouragement in the fact that bare metal 
l^egan rusting in a few hours, and rust spots began developing on 
poorly protected surfaces in from a few days to a week. 

The fact that more troul^le is experienced with trolley-line sus- 
pensions along the seashore than with the same devices inland, led 
immediately to the trial of an atmosphere saturated with salt water, 
. with astonishingly satisfactory results. 

As* now used, the test consists in exposing the Sherardized ar- 
ticles in a copper-lined box, such as is illustrated in Figs. 133 and 
134, into which there is projected by compressed air an atomized 
spray of 2| per cent, solution of NaCl in water. Care is taken 
to avoid placing the test specimens directly in the path of the jet. 
To insure constant saturation, an excess of salt is kept in the water 
at the bottom of the chamber. The spray is produced by a jet of 
compressed air lifting the water to the nozzle, whence it is pro- 



CALVANIZING SPECIFICATIONS AND TESTS 



307 



joeted as a cIoikI. Tliis apparatus is of tlio comnioii atomizer 
typo. The ehaiuber is necessarily not tightly sealed, but is open 
sudieiently to permit "breathing"; when used with an air jet, 
there is a slight pressure which is relieved through the Ijreathing 
openings. If desired, the test may be modified by the use of a 
line steam jet to raise the temperature of the atmosphere in the 
c-hamber. The specific gravity of the water is kept at 1.036 
and 1.03 at 60 deg. F. There is also the possibility of render- 
ing the test atmosphere slightly acid or alkaline by suitable addi- 
tions to the Avater in substitution for the salt. For use with plain 
water, the closet generally used for cement testing does very well, 
provided care is taken that it is so arranged as to maintain the air 
practically at 100 per cent, relative humidity. When using salt 
solutions, recourse must be had to the atomizing jet to insure the 
development of the salt fog. 



OuncBs per Square Foot of Surface 



33 



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Salt Spray Test Hours iv show Rust Evidence 
Chart III. Record of Comparative Tests 



When exposed as described, articles have a very thin film of 
moisture o\er their surface, but there should be very few, if any, 
drops of sensible size on the objects. Obviously, the test is very 
searching, as all parts of the surface are exposed, and any pin holes 
or uncovered areas become evident. This gives one an opportunity 



308 GALVANIZING AND TINNING 

to learn something of the efficiency of any protecting process in 
talcing care of edges, sharp corners, porous spots in the metal sur- 
face, etc. By noting the character of the general final breakdown, 
a very good idea of the evenness of the coating applied may be 
obtained. 

The salt spray test, as it is called, has been used during the 
last four or five years, commercially, by the General Electric Com- 
pany as a check upon the products of its process of Sherardizing. 
The coated articles are exposed to the salt fog, and are exam- 
ined from time to time to note their service condition. When 
the coated material is iron in any of its several forms, red dust 
begins developing as soon as the coat breaks down. The appear- 
ance of red dust may be in small pin points which gradually ex- 
tend, or it may appear generally over the surface of the article. 
When the coating is relatively thin and poor, rust may develop in 
from two to three hours to tAventy-four hours, or longer. A 
better coat will last two or three days, but a well-applied coat of 
requisite thickness will last at least a week. If no rusting is 
developed in this time, it may safely be assumed that the life of 
the coating will be practically indefinite. These figures are based 
on experience with both Sherardizing and galvanizing. 

This method of testing Sherardized articles is offered in replace- 
ment of the Preece test. Some reasons for this may be seen by 
referring to Chart III. As an example, we may take a sample 
with a deposit of .1377 oz. per square foot of surface, which has 
stood three dips in the Preece test, and a sample with .7 oz. per 
square foot of surface, or .5693 oz. more, which stood only 7 dips 
when it should have stood 11 or 12. The salt spray test is onl}^ 
an exaggeration of what may be expected at the seashore and 
differs only in degree, not in kind, from the normal conditions 
under which the article is intended to be used. 

Hydrochloric Acid and Antimony Chloride Test for Sheets 

and Wire 

Mr. J. A. Aupperle, metallurgical engineer, American Polling 
Mill Company, Middletown, Ohio, offers a new method for testing 
the spelter coatings of sheets and wire in a pa]3er read before the 
American Society for Testing Materials, Atlantic City, N, J., 
June 22, 1915. 

It has been customary to express the weight of coating on wire 



GALVANIZING SPECIFICATIONS AND TESTS 



309 



ill pounds per mile, while on sheet products the results are usually 
expressed in ounces per square foot. Obviously, tlie coating on 
wire expressed in pounds per mile would have a different meaning 
for each gauge of wire. If the results are expressed in ounces per 
square foot of surface on both wire and sheets, there will he a better 
understanding as to the thickness of coating on the respective 
])roducts. In stating the weight of coating on galvanized sheets it 
is customary to express the weight hased on one surface only, that 
is, a sheet containing 2 oz. of coating per square foot really contains 
1 oz. on each side of the sheet. 




Fig. 13.3. Salt Spray Testing Box 

It is proposed to express the weight of coating on Avire in ounces 
per square foot, and also to use such lengths of wire that the num- 
ber of grams of coating found will he equivalent to ounces per 
square foot, without calculation. These lengths must be such that 
the surface coated is equal to 5.079 sq. in. It is likewise proposed 
that the samples for determining the weight of coating on galvan- 
ized sheets shall be 214x2^4 in. (area == 5.079 sq. in.). The 
number of grams of coating on a section of this size will also express 
the weight of coating in ounces per square foot without calculation. 



310 GALVANIZING AND TINNING 

Tlie method for determining tlie weight of spelter coating consists 
of using a small amount of antimony chloride in hydrochloric acid 
(sp. gr. 1.20). Antimony chloride appears to hasten the solution 
of the coating, and after the coating has dissolved a thin film of 
antimony plates on the surface of the hase metal and retards the 
solution of iron or steel. Experiments have shown that sheet steel 
2^/4 X 214 in. which loses 50 mg. in five minutes in cold hydrochloric 
acid (sp. gr. 1.20), will lose in that time only 1 mg. in the same 
acid containing 80 mg. of antimony per 105 c.c. of acid. 

Determining Spelter Coating of Sheets 

In the proposed method the metal is immersed in the acid only 
one minute, which is long enough to dissolve several grams of 
coating, yet the amount of iron or steel dissolved is negligible. The 
small amount of antimony that plates on the surface of the sample 
can easily be removed by scrubbing under running water. This 
method is one of the most rapid and accurate with which the writer 
is familiar, and a determination can be made in less time than is 
occupied in making the Preece test. 

For determining the weight of coating on galvanized sheets cut 
several samples 214 x 214 in. from various parts of the sheet. These 
samples, about five in number, should be weighed together and im- 
mersed singly for 1 in. in 100 c.c. of hydrochloric acid (sp. gr. 
1.20), to which has been added 5 c.c. of antimony chloride prepared 
by dissolving 20 g. of antimony trioxide in 1,000 c.c. of hydro- 
chloric acid (sp. gr. 1.20). The same 190 c.c. of hydrochloric acid 
can be used for at least five samples. Five cubic centimeters of the 
antimony chloride, however, should be added for each sample on 
account of the antimony being removed from the solution by the 
iron. 

The samples are washed and scrubbed under running water, 
drie'd with a towel, and laid in a warm place for a few seconds. 
The samples are again weighed together and the number of grams 
lost is divided by the number of samples taken. Each gram cor- 
responds to 1 oz. of coating j^er square foot. 

Determining Spelter Coating of Wire 

A small section of the galvanized wire should be stripped in 
hydrochloric acid containing antimony chloride. The diameter 
of the black wire should then be carefully measured in order to 



OALVANiZlN(} SPKCIFK'ATIONS AND TESTS 



311 



clciermiuG the length of wire, sucli tliat the niimher of grams of 
coating will represent the number of ounces per square foot of 
surface. 

ed/ahrass So/dez-ed To ang/e brass as spacers Co Aeefi 

g/assAars /n/tos/t/on the ent/re /ertgtfi of box 




/r>ter/or of 60* arid cOk'ers copper 
/tried ana a// jo/r}ts ^o/dsred 



Coirer removed 



Airpipe 



Spray Atoiz/e 





36' «-1 

Fig. 134. Details of Construction of Salt Spray Testing Box 



The method of making the test is very similar to that outlined 
for galvanized sheets, except that the wire is first cleaned with 
carbon tetrachloride or gasoline, and after being carefully weighed 
is placed in a tall glass cylinder containing hydrochloric acid (sp. 
gr. 1.20), to which has been added from 2 to 3 c.c. of antimony- 
(^hloride solution of the same strength as used on galvanized sheets. 
The reason for using one-half the amount of antimony chloride 



312 GALVANIZING AND TINNING 

in the case of wire is on account of taking one-half the area. As 
previously stated, the coating on galvanized sheets is expressed in 
ounces per square foot, considering one side only, when in reality 
this amount of coating represents 2 sq. ft. of surface. After im- 
mersing the entire length of wire for 1 min. it will be found con- 
venient to pour the acid solution into another tall cylinder in order 
to facilitate removing the wire. The wire is then scrubbed under 
running water, wiped, thoroughly dried in a warm place for a few 
seconds and again weighed. Each gram lost corresponds to 1 oz. 
of coating per square foot. For direct comparison with the weight 
of coating as expressed on galvanized sheets, this figure should be 
doubled. 



INDEX 



Acetate, Sodium, in Elec.-Galv. 

solution 221 

Acid consumption in pickling.. 46 

Hydrofluoric 43 

Hydrofluoric pickle 212 

in porous castings effect in 

Sher 279 

Muriatic 43 

Muriatic, pickle 211 

Nitric, pickle 211 

Preventing waste of 280 

Sulphuric in Elec.-Galv. solu- 
Sulphuric in Elec.-Galv. solu- 
tion 219. 220, 221 

Sulphuric, pickle 211 

tanks, Construction of 30 

Tartaric, in Elec.-Galv. t-olu- 

tion 22J 

Action of gas in metal. 229 

Agents for improving Elec.- 
Galv. solutions 22>i 

Agitatioa of solution Elec.- 
Galv 153 

Air pressure in Schoop process 102 
trapped in tubes, Prevention 

of 194 

Alcohoi, Its effect on Elec.-Galv. 

bath 222 

Alum, Effect on Elec.-Galv. 

bath 222 

Aluminum 43 

Chloride, Sodium in Elec.- 
Galv. solution 221 

coating by Schoop process.. .. 96 
improves appearance of work 43 
Sulphate of, in Elec.-Galv. 

solution 218, 220, 221, 222 

Ammonia absorbed by charcoal 229 
Ammonium chloride in Elec.- 
Galv. solution 218, 219, 220, 221 
chloride, Zinc, Substitute for 

sal ammoniac 42 

Amperage for Elec.-Galv. 

1.53, 218, 219 
required under different con- 
ditions 207 

Analysis of zinc dust 274 

Anchors, Ashler Hot Galvanized 11 

cleaned by sand blast 59 

Angles,. Casting's with sharp 
angles, require special pre- 
paration 133 



Annealing' action in Sher. 

furnace 277 

Anodes 149, 189, 199, 203, 222 

Automatic removal of 164 

Choice of 207 

Cleaning scum from 164 

Special shapes for depi-es- 

sions 223 

Wrapping, to galv. inside of 

tubes without contact 193 

Antimony chloride and hydro- 
chloric acid test 308 

Apperance of work improved 

by aluminum 43 

Applying zinc coating by Elec- 

Galv. process 222 

Ash can for zinc dust 233 

cans. Temp, for Hot Galv. of 68 

pit - 17, 25 

Ashler anchors, Hot Galv 11 

Ashes, Zinc, How formed 90 

Asphalt lined tanks 208 

Asphaltum, Use of, in tank con- 
struction 31 

B 

Band iron. Formula for Elec.- 
Galv. of 218 

Schulte machine for Elec.- 
Galv 204 

Bars for Potthoff machine, 

Elec.-Galv 191 

Barrel, Dry tumbling, Loading 

of 52 

Unit for Elec.-Galv. a modi- 
fied form 181 

Unit for Elec.-Galv., Opera- 
tion 181 

Barrels, Elec.-Galv. 

Cleaning, rinsing and plating 

unit 177 

Daniel's hand and lever 165 

Ele-Kem automatic 174 

Potthcff's automatic 168 

Schulte's mechancial 172 

Unloading automatically..l68-173 
Barrels, Sand blast 

Details of construction 63 

Operation of 61 

Barrels, Tumbling 

Charging of 54, 213 

Construction of 53 

Detailed plan of 53 



314 



INDEX 



Barrels, Tumbling 

Elevation of 53 

Loading of 54 

Basins Catch under acid and 

water tanks 15 

Baskets .-31, 118 

for tinning small articles, 

Construction of 118 

Bath, Hot alkali, for cleaning 
gray iron castings for 

tinning 135 

showing acid reaction the best217 
Baths, Cleaning and pickling..210 
Bayliss process for Hot Galv- 

sheets - 76 

Beams, Steel grillage, Hot 

Galv -- 10 

Benzoic acid, its effect on Elec- 

Galv. bath 222 

Black pickling 46 

spots, Eliminating, from fin- 
ished work - - 279 

spots on Sher. articles, 

Cause of 279 

Blue dust. Advantages of 257 

Metallic content 267 

Takes longer to cool 257 

"Blue powder" — zinc dust.... 256 
Boiling out kettles. Tools for 93 
"Boiling" the tin in re-tinn- 
ing 127 

Bolts, Allowance for thickness 

of coating in Sher 268 

Equipment for Sherardizing 233 
Boric acid in Elec.-Galv. solu- 
tion 218, 219, 220 

Box, Testing, for salt spray 

309, 311 
Boyles and Charles, Law of.... 229 
Bricking in a small galv. kettle 20 
Brickwork on galvanizing kettle 
without grates and having 

one draft hole 26 

Bronze, Depositing on Sher. 

articles 282 

Brushing, Objection to, in test- 
ing Sher 298 

Scratch - 211 

surplus zinc from article.... 70 

Buffing Sher. articles 282 

Burnishing barrel, Ele-Kem.... 175 

Sher. articles 282 

By-products of Hot Galv. pro- 
cess .-• - 84 

©f Hot Galv. process, Ke- 

covery 85 

C 
Cable or chain conveyer ma- 
chine, Fleischer's 161 

strip, armored, Test for 
thickness of zinc coating.. 226 



Car, Transfer, Construction of 253 
Cartridge steel, Elec.-Galv. of 194 

Casing for draft holes 24 

Castings, Avoid sharp angles 133 
Cast-iron, Preparing for tum- 
bling 54 

Cleaning 210 

Drying, Arrangement for.... 26 

Elec.-Galv. solution for 219 

for grate fired Galv. kettle.. 23 

for small Galv. kettle 21, 22 

for tinning kettle 116 

Gray iron, Cleaning with hot 

alkali bath 135 

Gray iron, Heat required in 

tinning — 142 

Gray iron, Preparing for tin- 
ning 133 

Gray iron, Eemoving sand 

from 133 

Gray iron, Removing sand 

with hydrofluoric acid 134 

Gray iron. Time required to 

tin 141 

Gray iron. Tinned for electro 

plating 136 

Gray iron, Tinning of 129 

Handling delicate ones in roll- 
ing barrel 57 

Malleable and gray iron, 

Pickling of 263 

Method of immersing in 

roughing kettle 140 

Over-pickled, Remedy for ....135 
Sandy, Cleaning with hydro- 
fluoric acid 113 

Sandy, Cleaning with sul- 
phuric acid 49, 112 

Sandy gray iron. Cleaning 

with sand blast 135 

Sandy gray iron. Cleaning 
with sulphuric acid for tin- 
ning 135 

Solution for finishing when 
work is not thoroughly 

cleaned 55 

Storing after tumbling 57 

Testing to see if they are 

properly cleaned 55 

Time required to clean in 
tumbling barrel and sand 

blast 55, 59 

Time and speed required to 
clean in tumbling barrel 55 
Cast iron, Preparing for tin- 
ning 54, 133 

Catch basins under acid and 

water tanks 15 

Caustic-soda solution 210 

Caustic-soda test 293, 303 

Ceiling, High, for plants 14 



INDEX 



315 



Cement floor, Advantage of 233 

Chain or cable conveyer ma- 
chine, Fleischer's 161 

conveyer machine, Miller's, 

Construction of 153 

conveyer machine, Miller's .. 156 
Equipment for Sherarclizing 233 
Grips, Removing scale from 211 
Cleaning, in dry tumbling 

barrel 53 

Chamber pails, Temp, for Hot 

Galv. of 68 

Charcoal, Absorption of am- 
monia 229 

Charging of tumbling barrel 

54, 213 
Charles and Boyles, Law of.— 229 
Chart, Deposit and temp, in 

Sher 270 

Chilled shot used instead of 

sand in sand blasting 64 

Chimney construction for Hot 

Galv. plant 17 

Chloride, Ammonium, in Elec- 
Galv. solution, 218, 219, 220, 221 
of ammonia in Elec.-Galv. 

solution 218, 219, 220, 221 

Sodium, Aluminum in Elec.- 
Galv. solution 221 

of zinc in Elec.-Galv. solu- 
tion 218, 219, 220, 221 

Cinder test for Galv. coating 225 
Citrate, Sodium, in Elec. Galv. 

solution 221 

Cleaning barrel 51, 174, 177 

castings with sulphuric or 

hydrofluoric acid 49 

Electro 215 

equipment 149 

most essential step in Sher- 

ardizing 232 

old galvanized work 146 

old tinned work 146 

Potash solution for 196 

Einsing and plating units, 

168, 172, 177 
Rinsing and plating barrel 

unit, A modified form 182 

scum from anodes 164 

Sher, articles 280 

Spec, for ; 287 

Tanks 208 

work for Elec.-Galv 209 

Cloth, Wire, Formula for Elec.- 
Galv. of 218 

King's machine for Elec.- 
Galv 194 

Root's machine for Elec.- 
Galv 202 

Coal hods. Temp for Hot Galv. 68 
Time required to Hot Galv. 70 



Coal, Pea, Cost of, in Sher. one 

ton 285 

Coating, Spelter of Sheets, 

Determining 310 

Zinc, Applying in Elec.-Galv. 

Process 222 

Zinc, Locating cracks in 294 

Zinc, Non-uniformity in Sher. 

Remedy for 279 

Coke 43 

Burning, Sher. furnaces 234-240 
Cost of in Sher., one ton.... 285 
Dust, Use of, in Hot Galv. 

wire, etc 77 

Foundry unsatisfactory 43 

Gas gives best results 43 

Cold or Elec.-Galv 148, 226 

Colloids 222 

Coloring and finishing Sher. 

articles - 282 

Combination formula for clean- 
ing and plating 216 

Combustion chambers in gas 
and oil burning furnaces 241 
in Goke burning Sher. fur- 
nace 234 

in Sher. furnace 238 

Conductors, Copper 149 

Rule for figuring size of 207 

Construction of three drum 
coke burning Sher. furnace 

234 
Cooling and unloading drums 276 

Drums 271 

Frame 233, 255 

Hot Galv. work 70 

Out 276 

platform .....247, 248 

Rapid, Eifect of 275 

Slow, better than fast in 

Sher 273 

Coping plates 25 

Copper acid solution 225 

Bath 198 

Cyanide bath 225 

Cyanide bath, action of 212 

Cyanide strike 211 

Depositing, on Sher. article 282 

Dip. Formula for 212 

Flashing 211 

Sulphate or Preece test 

290, 294, 301 
Correct position of pyrometer 

in kettle 35 

Corrosion of iron and steel. 

Prevention of 9 

Theory of 11 

Corset steel Elec.-Galv. of, 194, 225 
Cost of Elec- and Hot Galv.. 224 
of coating with zinc by Schoop 
process 102 



316 



INDEX 



Cost of coke in Sher. one ton 285 

of elec. current 224 

of Elec.-Galv 208, 224 

of illuminating gas in Sher.. 285 
of metal spraying with "pis- 
tol" 105 

of oil 284 

of producer gas in Sher. 

one ton 285 

of production (all processes) 72 

of Sher. per ton 284 

of zinc dust 284 

Cowper-Cowles Sherard, In- 
ventor of Sherardizing pro- 
cess 227 

Cracks, Locating in zinc coating294 

Cyanide, Copper bath 225 

fumes. Removal of 150 

Cyclone metal spraying device. 

Operation of 98 

D 
Dairy utensils, Coating, by 

Schoop process 104 

Daniel's Elec.-Galv. barrel 165 

Screw conveyer machine 158 

Davies' method of Galv. sheets 

74 
Defective coating frequently 

due to poor cleaning 209 

Density of Elec.-Galv. solutions 219 

Deposit, Heavy in Sher 275 

Deposition, Double 223 

Dextrine in Elec.-Galv. solu- 
tion 220 

Effect of, on Elec.-Galv. 

bath 222 

Dip, Formula for copper 212 

Dipping gray iron castings in 

tin 138 

in molten zinc. Time requir- 
ed 69 

Preparing cleaned work for 64 

work in molten zinc 69 

Dont's in Sher. practice 278 

Double deposition 223 

Drainage of Hot Galv. plant 15 

of tinning plant 109, 130 

Drier, Front section of 27 

grate and firebox. Detail of 30 

Operation of 65 

Placing work in it to keep hot 

without burning acid off.... 65 
Plan and details of construc- 
tion 28 

Plan and elevation of 29 

Plates covering fires will do 
for small lots of work.... 65 

Proper location of 65 

Dross, Hard zinc 84 

Kept from coming in direct 
contact with bottom of 



kettle by 6 or 8 in. layer of 

lead 66 

on re-tinned article, Method 

of preventing 125 

Remelting 145 

Removal of, from tinning 

kettle 141 

scoop. Construction of 33 

Storage of 145 

Value of 145 

Zinc, How formed 85 

Zinc, Method of recovering.. 85 
Zinc, sweating. Temperature 

and operation 88 

Drums, Cooling 271 

Cooling and unloading 276 

Loading 261, 263, 266 

Loading into furnace 254 

Rotation of, in Sher. furnace 

237, 267, 273 

Sherardizing 233, 250, 251 

Sherardizing, Construction of250 
Sher. Cylinder, fastening 

heads on 251 

Sher., Square 250 

Dry Galv. or Sherardizing 227-286 

tumbling 52, 209 

Tumbling of wire work 213 

Drying apparatus 27, 65, 200 

Barrel Ele-Kem 176 

Castings, Arrangement for.. 26 

Hot Galv. work 71 

plate 17 

work after tumbling and 

sand blasting 65 

of heats in Sher 267 

Duration of Elec.-Galv 225 

Dust screening machine 

233, 251, 276 
Dynamo 206 

E 
"Edis Compound," A substitute 
for sulphuric acid in dry 

cakes 48 

Egg beaters, Tinning of 129 

Electric current. Chart for 

Sher - 271 

Hoist for Sherardizing plant 234 
Electrical condition accompany- 
ing evolution of gases 230 

equipment 206 

installation 150 

Electrically heated Sher. fur- 
nace 248 

Electro-cleaner, Action of 212 

Electro-cleaning 215 

Cleaning solution 211 

Elec.-Galv., Advantages of.... 148 
Barrel Unit with Cleaning 
and Rinsing tanks 177 



INDEX 



317 



Elec.-Galv. Apparatus 

Daniel's Screw conveyer 158 

Fleischer's Cable or Chain 

Conveyer 161 

Hanson & Van Winkle's Pipe 

and Tube 189 

King-'s Continuous Wire Cloth 

194 

Meaker Continuous type 184 

Miller's Chain Conveyer 153 

Potthoflf's Tube 191 

Eoot's Wire Cloth 202 

Schulte's Wire 204 

Elec.-Galv. Barrels 

Cleaning, rinsing and plat- 
ing unit 177-182 

Daniel's hand and lever 165 

Ele-Kem automatic 174 

Potthoff' s automatic 168 

Schulte's mechanical 172 

Elec.-Galv. or cold process. .148-22G 

Cost of 208, 224 

Duration of 225 

Earliest record of 148 

Heavy deposit 223 

Elec.-Galv of corset steels 225 

Open tank work 153-165 

Plant, Layout of 150 

Plant, Eemoving fumes 150 

Preparing work for 209 

Solution for castings 219 

Solution for soft deposit 220 

Solution for testing 287 

Solutions 217-222 

Solutions, Agents for improv- 
ing 222 

Solutions for barrel plating 219 

Spongy deposit 223 

Tests, Table of 304 

Time required, 218, 219, 222, 223 
vs. Hot Galv. comparative 
costs 224 

Electro plating. Gray iron cast- 
ings tinned for 136 

Electrolytic test 302 

Elec.-Galv. barrel saw-toothed 
construction 174 

Elevation of re-tinning plant 

containing four kettles.... 122 

"Embalming," or protecting 
iron from rust 9 

Emery, Use of in tumbling.... 218 

Epsom salts in Elec.-Galv. 
bath 220 

Equipment and plant for Hot 

Galvanizing 14, 17 

Electrical 206 

for Elec.-Galv. plant 149 

and location of Sher. plant 233 

Erlenmeyer flask. Use of 258 

Exhaust for dust screener 252 



F 

Fats will redeposit in Sher 281 

Filling a new kettle 66 

Finishing and coloring Sher. 

articles 282 

of re-tinned work 127 

Firing a new kettle 67 

Flaking, Cause of in Sher 281 

Flashing Copper 211 

Flat stock. Loading in Sher. 

drum 265 

Fleischer's Cable or Chain con- 
veyer Machine 161 

Floor Cement, Advantage of 233 

Floor space required for Sher. 
plant of one ton capacity 233 

Flues, Arrangement of 28 

Underground 17 

Flux boxes on Hot Galv. Ma- 
chines 74 

Exercise care in removing.... 89 

formed by sal ammoniac 42 

for tinning kettle in coating 

cast iron 139 

"Flux guard" 70 

in kettle 73 

prevents zinc from oxidizing 69 
Thick or lumpy, To remedy 139 
Food choppers, Time required 

for sand blasting 59 

Forgings, Pickling 48 

Formula for cleaning and plat- 
ing 216 

for copper dip 212 

for Elec.-Galv. solutions .... 218 
Foundation washer, Cast iron 25 

Frames, Cooling 233, 255 

Loading 233 

Fuel for tinning 107 

Proper depth in firebox 67 

Fumes 217 

carried off by exhaust sys- 
tem 150 

a menace to machinei-y 14 

Furnace, Gas, single drum 240 

Sherardizing 233 

Sher. Coke burning, Elev. 

and details of single drum 238 
Sher. Coke burning, Elev. 
and details of three drum 235 

Sher. electrically heated 248 

Sher. Elec. heated, Opera- 
tion of 271 

Sher. for long job work 244 

Sher. Gas and oil burning 

239, 248 
Sher., Loading drums into 254 

G 
Galvanic action taken up by 
zinc , 12 



318 



INDEX 



Galvanized work, old, Cleaning 

of 146 

Galvanizing, kettles allowed to 

cool off not economical 13 

Sheets, Construction of ma- 
chines for 74, 75 

Sheets, Heathfield method.... 75 
Sheets, Three process de- 
scribed 12 

Specifications 287 

Test, Government 303 

Gas, Action of, in metals 229 

Gas and oil burning Sher. fur- 
naces 239-243 

Bubbles in Elec.-Galv. Pre- 
vention of 203 

Contents of metals 228 

Illuminating, Cost of, in 

Sher 285 

Pressure of in Schoop pistol 101 

Producer, Cost of in Sher.... 285 

Gelatine, Use of in Elec.-Galv 222 

Generator, Location of 207 

Low voltage 149 

Girders, Coating by Schoop 

process 104 

Glucose, Effect on Elec.-Galv. 

bath 222 

Glue, Effect on Elec.-Galv. 

bath 222 

Glycerine 43 

Action of, in kettle 69 

in Elec.-Galv. solution 220 

Use of in making flux foam 

up 70 

Grape sugar in Elec.-Galv. solu- 
tion 218, 221 

Grasselli dust 256 

Dust, Advantages of 257 

Dust, Metallic content „... 267 

Grate and firebox for drier. De- 
tails of 30 

and firebox for tinning kettle 

131 
bars, Method of setting in 

tinning kettle 116 

fired galvanizing kettle, De- 
tails of construction 23 

Grates 24, 25 

Gray iron and malleable cast- 
ings. Pickling of 263 

iron castings, Preparing for 

tinning 133 

iron castings, Proper tem- 
perature for Hot Galvan- 
izing 68 

iron castings, Removing sand 

from 133 

iron castings. Removing sand 

with hydrofluoric acid. 134 

Grease or oil. Removal of........ 210 ' 



Grease or oil, Removal of from 

stamped ware 122 

Removing from work to be 

tinned 114 

Grillage beams, steel, Hot 

Galv 10 

Grinding and scouring machine 

213 
Grit, Diamond, Advantage of 64 

LTse of in wet tumbling 213 

used instead of sand in sand 

blasting 64 

Gum tragacanth in Elec.-Galv. 
solution 221 

H 

Handling pickled work 48 

Hanson & Van Winkle Pipe 

and Tube Galv. Machine.. 189 
Hardware Saddlery, Time re- 
quired to clean by sand 

blast 59 

Saddlery, Tinning of 109 

Testing samples 288 

Heathfield's method for Galv. 

sheets 75 

Heathfield Process, Zinc de- 
posited on sheets by 76 

Heat Controlling in Sher. fur- 
nace 238 

Heating kettles 147 

Heats, Duration of in Sher.... 267 
Heavy deposit in Elec.-Galv. 

process 223 

Hoist, Electric 280 

Electric, for Sherardizing 

plant 234 

Hood, Exhaust, for dust sep- 
arating machine 252 

Hoods for kettles and tanks, 

size of 15 

for kettles. Movable 14 

Hoop iron, Elec.-Galv. of 194 

Hot Galv. automatically 74, 76, 77 

Dipping the work 69 

Equipment 17 

Laws of physics applying to 18 

Plant and equipment 14 

Plant, Floor plan of 15, 16 

Plant, small 17 

Plant, steam required 15 

Plant, Ventilation of 14 

Plants, Drainage of 15 

Room fittings 14 

Solution for testing 287 

Tools, Construction of 32 

Tools for 31 

Work, Cooling after dipping 70 

Hot rolled steel. Cleaning 209 

Hydrochloric acid and antimony 
test 308 



INDEX 



319 



Hydrofluoric acid 43 

best for removing sand from 

gray iron castings 134 

Cleaning sandy castings with 

113 

Pickle 212 

Pickle, Test of 263 

Tanks for 16 

Use of in cleaning castings 49 
Hydrogen absorbed by pladium 229 
Hydrogen gas causes damage 80 
Remedying damage caused by 

80 
I 
Ice cream freezers, Tinning of 129 
Impurities lower melting point 36 
Inspection of material before 

Sher 279 

Ions, Free, Effect on precipit- 
ation of vapor 230 

Iron and steel, Comparative 
value for making Galv. 

kettles - 20 

Corrosion, Prevention of 9 

Iron Band, Elec.-Galv. of 204 

Formula for Elec.-Galv. of 218 
Iron, Cast, Preparing for tin- 
ning 54, 133 

Iron, Determining amount of 

in Galv. coating 292 

Malleable and gray, Pickling 

of 263 

Proper grade for making Hot 

Galv. kettles 18 

Sulphate in Elec.Galv. Solu- 
tion 221 

Wrought and steel, soluble 

value of 18 

Zinc Alloy 227 



Japanning, Sher. articles 282 

K 
Kettles, boiling out, Tools for 93 
Burst by allowing them to 
cool with quantity of zinc 

dross in them 86 

Filling new 66 

for molten zinc 16 

for recovering zinc dross. 

Construction of 87 

for refinishing old galvanized 

and tinned work 147 

for retinning 121 

for tinning 109 

for tinning gray iron cast- 
ings. Arrangement of grate 

bars and ash pits 131 

for tinning gray iron cast- 
tings, Elevation of— 131 



Kettles for tinning gray iron 

castings. Size and shape 144 

for tinning spoons, etc., Size 

of 119 

for tinning wire 119 

Galvanizing, allowed to cool 

off not economical 13 

Galvanizing, Bricking in 20 

Galvanizing, Castings for.... 21 
Galvanizing, grate fired, cast- 
ings for 23 

Galvanizing, grate fired. Con- 
struction of 23 

Galvanizing, grate, fired, plan 

and elevation 22 

Galvanizing, One piece 25 

Galvanizing, Selection of 20 

Galvanizing, Setting small, 

without ash pit 20 

Galvanizing without grates, 
one drafthole, Plan and 

elevations 26 

Galvanizing, Heating sides 

and bottoms of 147 

Galvanizing, Leaks in new 

or old 92 

Galvanizing, Life of 92 

Galvanizing Listing, Use of 126 
Galvanizing, New, Firing .... 67 
Galvanizing, New often 

ruined by improper filling 66 
Galvanizing, New, Packing 

slabs of spelter in 6Q 

Galvanizing, Preparing, be- 
fore starting to dip 69 

Galvanizing, Replacing old.. 92 

Re-tinning, Replacing 128 

Roughing 140 

Galvanizing, Selection of 

best material for making 18 
"Skinning" for removing sur- 
plus tin in re-tinning 127 

Soaking 121 

Tinning, Castings for. 116 

Tinning, Materials used in 

constructing 144 

Tinning, Plan and elevation 

of 115 

King Continuous Wire Cloth 

Machine 194 

"Kleanrite," a substitute for 
sulphuric acid in powdered 
form 48 



Labor cost in Sher 284 

in Sher. Improving 280 

Skilled more reliable than py- 
rometer on miscellaneous 
work 34 



i 



320 



INDEX 



Labor, Unskilled expensive in 

Hot Galv 13 

Lacquer finish on Sher. articles 283 
Laundry machinery, Coating by 

Schoop process 104 

Law of Boyles and Charles 229 

Lead Acetate and Preece Tests 

Compared 301 

Lead acetate test 291, 299 

acetate Test, Advantages of 301 

Lead as cushion for dross 66 

lined tank 208 

lining in Tanks 31 

not electro positive 12 

Pig 42 

Leaking prevented in articles 

by tinning before plating 129 
Leaks in kettles, Repairing.... 92 
Licorice, Its effect on Elec- 

Galv. bath 222 

Lime solution to neutralize 

acid 262 

Lining tanks with sheet lead.. 31 

Listing kettle. Use of 126 

Loading drums 261, 263, 266 

Frame 233 

Platform 246 

wet tumbling barrel 54 

Location and equipment of 
Sher. plant 233 

M 
Machinery Used in Hot Galv., 

Composition of 18 

Magnetic oxide. Removal of 

from bath 210 

Malleable iron castings. Tem- 
perature for Hot Galv.... 68 

iron casting. Tinning of 106 

Materials used in Hot Galv.... 41 

used in Sher. 256 

Vapor tension of 230 

Mealcer Continuous Machine, 

Operation of 188 

Continuous Type Elec.-Galv. 

Machine 184 

Mechancial Elec.-Galv. appar- 
atus 153 

"Melting out" 67 

Melting point lowered by im- 
purities 36 

Melting point of zinc 35 

Metal, Action of gas in 229 

Powdered, Use of in metal 

spraying 96 

Metallic method of rust preven- 
tion 9 

Metallic zinc in zinc dust. Meth- 
ods for determining 258 

Metals are extremely porous 229 
Gas contents of 228 



Metals, Spraying, Position of 
apparatus in applying coat- 
ing 103 

Spray Process, Schoop 94 

Methods of producing zinc 

vapor 230 

Miller Chain Conveyer Ma- 
chine, Construction of 153 

Chain Conveyer Machine, Op- 
eration of 156 

Mill scale. Removal of 210 

Moist air test 226 

Molasses, Its effect on Elec.- 
Galv. bath 222 

Morf patent for spraying pistol 95 

Motion during Sher 273 

Muriatic acid 43 

A "safe" pickle 49 

Dip for a flux 64 

Formula for a quick pickle 50 
Mixture for cleaning castings 

in tumbling barrel 55 

Pickle 211 

Removing scale or rust with 

48, 113 
N 

Nails, Equipment for Sher 233 

Sher. test of 298 

Temperature for Hot Galv. 

of 68 

"Nesting" of articles prevented 

122 
Netting, Wire, Hot Galv. of.. 77 

Nickel solution 225 

Nitric acid pickle 211 

Non-metallic method of rust 

prevention 9 

Nuts, Testing coating of 289 

O 
Oil 43 

and gas burning Sher. fur- 
naces 239, 248 

Fuel, Cost of in Sher 284 

Mineral lard, best 43 

or Grease, Removal of 210 

Removing in Sher 281 

Old work quickly cleaned by 

sand blast 59 

One piece galvanizing kettle.. 25 

Open tank Elec.-Galv 153, 165 

Operating costs in Elec.-Galv. 224 
Operation of chain conveyer 

plating machine 156 

of elec. heated Sher. furnace 271 
of Meaker continuous type 

Elec.-Galv. machine 188 

of King's wire cloth machine 196 

of plating barrel unit 181 

of screw conveyer plating 
machine 160 



INDEX 



321 



Overheatinj? destroys kettle 37 

in tinning?, Effect of 144 

Over pickling 45, 47, 212 

Remedy for 135 

Oxide, Magnetic Removal of 

from bath 210 

of Zinc, Value of in Sher.... 231 
Oxygen absorbed by spongy 

platinum 229 

P 
Packing Elec. heated Sher. fur- 
nace 266 

Paint, Old, Removal of by tum- 
bling 53 

Removing from w^ork to be 

tinned 114 

Paints, Non-corrosive 10 

Paladium Hydrogen absorbed 

by 229 

Palm oil used vv^ith beef tallow 

gives good results 142 

Parson's patent for Elec.-Galv. 148 
Patents covering Schoop pro- 
cess 95 

Phvsics, Laws of, as applied to 

■ Hot Galv 18 

Pickle, Hot better than cold.. 210 

Hydrofluoric acid 212, 263 

Muriatic acid, A "safe" 49 

Nitric acid 211 

"Quick," Formula for 50 

Sulphuric acid. Test of 262 

Time required 210 

Pickled work. Handling 48 

Pickling 44 

Acid, Consumption in 46 

Best mechanical method 46 

Black 46 

Cold better than hot 50 

Foundry 49 

Fumes, Effect of in Sher.... 278 

machine, Automatic 45 

malleable and gray iron cast- 
ings 263 

Mechanical 44 

Over 45-47 

Over, Remedy for 135 

Securing uniform action with 

acids 44 

Sheets .....44-46, 111 

Solutions, Length of time 
they may be used satis- 
factorily 50 

Solutions, Temp, of 262 

Steel 261 

Tanks 233 

Temperature in using Hy- 
drofluoric acid 49 

Under 45 

White 46 

Wrought iron and steel 48 



Pin Holes filled by Schoop pro- 
cess 104 

Pipe and tube Galv. machine, 
Hanson and Van Winkle.. 189 
Cleaning conduit with sand 

blast 213 

Water Furnace for Sher 248 

Pipes, Galvanized 11 

Pistol, Distance it should be 
held from work in spraying 

103 
for metal spraying, construc- 
tion details 99 

for metal spraying, Opera- 
tion of 101 

for Schoop Metal Spray Pro- 
cess 98 

Table of operating costs for 

one hr. 105 

Pitch lined tanks 208 

Plans for Hot. Galv. plant.. 15, 16 

Plans of Elec.-Galv. plant 150 

of small galvanizing kettle.. 21 
showing brickwork of galvan- 
izing kettle 22 

Plant, Elec.-Galv 150 

and equipment for Elec.- 
Galv 149 

and equipment for Hot Galv. 14 
and equipment for tinning.. 106 
and equipment for tinning 

gray iron 129 

Plate Drying 17 

Plates 24 

Coping 25 

Platform Cooling 247, 248 

Loading 246, 248 

Plating and cleaning in combin- 
ation 216 

Platinum, Spongy, Oxygen ab- 
sorbed by 229 

Porous condition of metals 229 

Porter machine for removing 
surplus zinc 71 

Position and location of pickl- 
ing and cleaning tanks 233 

Potash solution for Elec.-Galv. 196 
Potthoff's Elec.-Galv. barrel.... 168 
Potthoff Tube Galv. Machine.. 191 
Powdered metals, Use of in 

metal spraying 96 

Precipitation of Vapor, How it 

occurs on metal 229 

Preece Test 290, 294 

Test, Limitations of 291 

Test, Objections to 297 

Test, Operation of 290, 294 

and lead acetate tests com- 
pared 301 

Preparing cleaned work for 
dipping in hot zinc 64 



322 



INDEX 



Preparing gray iron castings 

for tinning 133 

material for Sher 261 

work for Elec.Galv 209 

Prevention of corrosion 9 

Producer gas, Cost of in Sher. 285 
Protecting pyrometer from 

action of molten zinc 34 

Protection of iron from rust.... 9 
Pumice stone, Use of in clean- 
ing work 214 

Pure water test for Galv. coat- 
ing 225 

Pyrogallol, Its effect on Elec.- 
Galv. bath 222 

Pyrometer 233, 255 

important as temperature 

regulator 35 

in proper position 35 

of advantage on sheets, wire 

and other straight work.. 34 
Protecting stem from action 

of zinc 34 

Selecting a reliable one im- 
portant 37 

Stupakoff's paper on 35 

Use of in Hot Galv. kettle.. 34 

R 
Rack for re-tinning small 

articles 124 

Re-charging tumbling barrel- 55 
Reducing agents for Elec.-Galv. 

solutions 222 

Refinishing old galvanized and 

tinned work 146 

Regulation of zinc deposit 223 

of zinc deposit in Elec.-Galv. 223 
Remelt spelter vs. Prime 
western Calorific value of 68 

Removing oil or grease 210 

sand from casting 210 

Re-tinned work. Finishing 127 

Re-tinning kettles, Replacing.. 128 

Method of handling work 125 

plant and equipment — . 121 

plant containing four kettles. 

Elevation of 122 

plant with four kettles, Plan 

of 123 

Rack to prevent "nesting" of 

small articles 124 

stamped ware 121 

Rheostat, Adjustment of 161 

Rolling barrel for tinning gray 

iron castings _- 129 

improves appearance of tin 

coating 112 

water. Removing scale by 

51, 113, 136 
Wet and dry 51, 213 



Root Wir^ Cloth Machine 202 

Rotation of drums in Sher. 

237, 267, 273 

Roughing — ..' 119 

Rust preventative. Zinc, best.. 11 
prevention. Metallic method 9 
prevention. Non-metallic me- 

thod_ 9 

Removing 16 

Removing from castings with 
sulphuric acid Ill 

S 
Saddlery, hardware, Tinning 

of 109 

Sal ammoniac 42 

Action of, in kettle 69 

Dip for a flux 65 

Gray granulated forms flux 42 
in Elec.-Galv. solution....221, 222 
mixture for cleaning castings 

in tumbling barrel 55 

Skimmings 84 

Skimmings, Method of recov- 
ering 90 

Skimmings often shipped in 

bulk 90 

Skimmings, Storage of 89 

Saline or salt spray test.. ..225, 304 
Salts, Epsom in Elec.-Galv. 

solution 220 

Spray test 225, 304 

Spray testing box, Details 

of 311 

Samples for testing... .288, 292, 309 
Sand, Condition of, for sand 

blasting 64 

Removing from castings 210 

Removing from gray iron 

castings 133 

Removing from gray iron 

castings for tinning 135 

Sand blast barrel, Details of 

construction 63 

barrel. Operation of 61 

Rolling barrel 61 

Use of makes tinning of 

castings simple 58 

valuable in cleaning sandy 

gray iron castings 135 

Sand Blasting 58, 135, 213, 261 

Air pressures required 60 

and tumbling 51-65, 213 

Apparatus, Operation of 59 

Food choppers, Time requir- 
ed for 59 

Machine, Automatic rotary 

type - 61 

Machine, Single hose type.... 60 

Machine, Two hose type 59 

Protection of Operator in.... 62 



INDEX 



323 



Sand blasting 

quickly cleans "old" work.... 59 

Rev. per Min. in barrel 61 

Roof, Construction and ven- 
tilation of 62 

Saddlery hardware 59 

Superior on light and deli- 
cate castings 61 

Use of grit and shot instead 

of sand 64 

Value of, in Elec.-Galv. and 

Sher 59 

Sawdust in zinc, Effect of 281 

Use of in tumbling 213 

Scale, Removal of. Time requir- 
ed for 47 

Removing 16 

Removing by sand blast 

58-65, 213 

Removing by water rolling 51 

113, 136 
Removing from wire - 119 

Removing with muriatic acid 

48, 113 

Removing with sulphuric 

acid 47, 111 

Schoop Metal Coating Process 

Coating with aluminum by 96 
Schoop Metal Spray Process.- 94 
Detail of old stationary type 96 
Details of first portable appa- 
ratus 97 

Details of pistol 99 

Evolution of apparatus used 95 
Method of holding "pistol" 103 

of applying the coating 101 

Operation of first portable 

type of apparatus 96 

Operation of old stationary 

type 95 

Operation of the cyclone ap- 
paratus 98 

Pistol, Gas pressure required 101 

Pistol type of apparatus 98 

will fill pinholes and defects 

in sheets or coatings 104 

Schulte's Elec.-Galv. barrel 172 

Grinding and scouring ma- 
chine 213 

Wire Galv. machine 204 

Scoop, Dross, Construction of.. 33 
Scouring and grinding machine 213 

Scratch brushing 211 

Screener dust 276 

Screening machine, Dust. .233, 251 
Screw conveyer machine, 

Daniel's - 158 

Screws, Allowance for thick- 
ness of coating in Sher.... 268 
Equipment for Sher 233 



"Scruff" or dross, Method of 
handling work to prevent 

the attachment ox 125 

Setting small galvanizing kettle 

without ash pit 20 

Sheet steel. Temp, for Hot 

Galv. of 68 

Sheets, Bright Galv 74 

Determining spelter coating 310 
Formula for Elec.-Galv. of 218 
Hot Galv., by Bayliss pro- 
cess 76 

Hot Galv., by hand 73 

Hot Galv., Construction of 

machine for 74 

Hot Galv. of 73 

Material required to Hot 

Galv 75 

Pickling 44, 46, 111 

Schulte machine for Elec. 

Galv 204 

Sher. test of 296 

Tests of durability 225 

Sherard Cowper-Cowles, Inven- 
tor of dry Galv. process.... 227 
Sherardized steel magnified 100 

times 228 

Steel magnified 1300 times.. 229 
Sherardizing articles which 
cannot be successfully coat- 
ed 231 

Art of 227 

Cause of black spots in 279 

Cause of unsatisfactory 232 

Cleaning most important op- 
eration in , 232 

Cleaning very essential 280 

Coloring and finishing 282 

Cost per ton 284 

Cutting down screws and 

threads 267 

Definition of 228 

Depositing copper or bronze 

after 282 

Discovery of 227 

Dont's in practice 278 

Drums 233 

Drums, Life of 250 

Fats will redeposit in 281 

Flaked work cause of 281 

Furnace 233 

Fui-naces, Coke burning-234-240 
Furnaces, Controlling heat of 238 
Furnaces, Electrically heated 248 
Furnaces Elec. heated, Op- 
eration of 271 

Furnaces, Elec. heated, Pack- 
ing 266 

Furnaces, Gas and oil burn- 
ing 229-248 

General operation 275 



324 



INDEX 



Sherardizing 

Heavy deposit 275 

in prehistoric times 227 

Inspection of material before 279 

Japanning after 282 

Lacquering over 283 

Materials used in 256 

Motion during 273 

Must not be done in same 

room as pickling 278 

Nickling over 282 

Non-uniformity of coating 

remedied 279 

Not a solder 281 

or dry Galv 227-286 

Plant, Floor space required 

for daily capacity of one 

ton 233 

Plant, Location and equip- 
ment of 233 

Plant, Typical floor plan 233, 234 

Preece test for 294 

Preparing material for 261 

Pure zinc gives best results 231 

Temp, and deposit chart 270 

Temp, in 256, 257, 262, 267, 

270, 275, 279 

Temp. Uneven effect of 279 

Test, Salt spray 225, 304, 311 

Testing by electrolytic meth- 
ods 302 

Theory of 228 

Time required for..257, 272, 275 

Value of zinc oxide in 231 

Various stages of 231 

with Zinc under vacuum 272 

Shot used instead of sand in 

sand blasting 64 

Sinks, Temp, suitable for 
Galv 68 

Size of conductors. Figuring.. 207 

Skimmer, Use of 89 

Skimmers 32 

Skimming kettle for rem_oving 
surplus tin in re-tinning.. 127 

Skimmings, Dry zinc 84 

Sal ammoniac 84 

Sal ammoniac, Recovering.. 90 
Sal ammoniac, Storage of.. 89 
Slabs of spelter, Arrangement 

of in kettle 67 

Slag burnt in, Efl'ect on Sher..279 
Slag, Removal of from tinning 

kettle 141 

Smooth coating, Agents which 

produce 222 

.secured by using grape 

sugar 218 

"Soaking'' kettle 121 

Soda, Caustic, Test 293, 303 



Sodium acetate in Elec.-Galv. 

solution 221 

Aluminum, Chloride in Elec.- 
Galv. solution 221 

Citrate in Elec.-Galv. solu- 
tion 221 

Sulphate of in Elec.-Galv. 

solution 218, 219, 220, 222 

Solution, Caustic soda 210 

for testing Elec- and Hot 

Galv 287 

Lime, to neutralize acid 262 

Solutions for Elec.-Galv 217-222 

for Elec.-Galv. in open tanks 218 

Pickling, Temp, of 262 

Spangled, Preparing work to be 68 
Spraying pistol, Details of 

construction 99 

Specifications, Galv 287 

Spelter, Coating of sheets. De- 
termining 310 

Coating of wire,Determining 310 
Packing slabs in new kettle 66 
Prime Western, vs. Remelt, 

Calorific value 68 

Selecting best for the pur- 
pose - 42 

Slab zins 41 

Spirella Go's Elec.-Galv. plant 150 

Spongy deposits, Cause of 223 

Spoons, Iron, Tinning of 109 

Steel Tinning of 119 

Stamped steel, Wet tumbling of 213 

ware, Retinning of 121 

Steel, Elasticity changed by 
temp, and length of dip.. 80 
and wrought iron, soluble 

value of 18 

Hot and cold rolled clean- 
ing of 209 

Pickling 48, 261 

Pipe, Temr). for Hot Galv. 

of 68 

Proper grade for making Hot 

Galv. kettles 18 

Sher. magnified 228, 229 

Stamped, Wet tumbling of.. 213 

Tinning of 106 

Sticking together of work, 

How prevented 71 

Storage tanks 48, 57 

Storing castings after tumbling 57 
Strength of wire influenced by 

Hot Galv 78 

Strike zinc - 223 

Stringing work for Hot Galv. 70 
Stupakoff", S.H., Paper on py- 
rometers ^5 

Sublimation 228 

Sugar grape in Elec.-Galv. 
bath 218, 221 



INDEX 



325 



Sulphate Iron in Elec.-Galv. 

bath 221 

of aluminum in Elec. Galv. 

solution 218, 220, 221, 222 

of copper test 226 

of sodium in Elec.-Galv. so- 
lution 218, 219, 220, 222 

of Zinc Elec.-Galv. solutions 

218, 219, 220, 221, 222 

Sulphuric acid 43 

Cleaning sandy castings..49, 112 
for cleaning sandy gray iron 

castings 135 

in Elec.-Galv. solution 

219, 220, 221 

pickle 49, 211 

Pickle, Test of 262 

Removing scale with... Ill 

Substitutes for 48 

Tanks for 16 

Test for Galv. coating.. 225 

Use in cleaning sandy cast- 
ings 49 

Use of in removing scale 47 

Surplus Tin, Method of remov- 
ing 118 

Removal of in "skimming" 

kettle 127 

Removing from wire tinned 

in coils 119 

Surplus Zinc, Removal by me- 
chanical means 71 

Removal of from wire cloth 77 
Removing from castings by 

brushing 70 

Removing from work dip- 
ped in baskets 71 

"Sweating" prevented in plat- 
ing by tinning first 129 

Sweating zinc dross 87 

Sweepings from Sher. plant.. 281 

Switchboard 149 

Switching box. Construction 
and use of 143 



Tallow in re-tinning kettle. 

Condition of - 123 

Tank for kerosene 118 

Tanks, coating by Schoop pro- 
cess 104 

for acid and water 30 

for caustic soda 114 

for cleaning sandy castings 

with Hydrofluoric acid.... 13 4 
for copper bath in Elec.- 
Galv 198 

for elec. cleaner 149, 215 

for Elec.-Galv. Construction 

of 208 

for tinning 107 



Tanks, Hydrofluoric 16 

Lining with sheet leads 31 

Pickling 208, 233 

Pickling and cleaning. Loca- 
tion 233 

Oil, Construction of 142 

Rinsing 114 

Sulphuric acid 16 

Washing 165 

Water 16, 108 

Wooden, Construction of 31 

Tannic acid, Its eff'ect on Elec.- 
Galv. bath 222 

Tartaric acid in Elec.-Galv. 

solution 221 

Tea kettles cleaned in tumbling 

barrel 54 

Temperature caustic Soda test 

293 303 

in Hot Galv 20, 36, 67, 68 

in Preece test.. 290, 294, 297 

in Sherardizing 256, 257, 262, 

267, 270, 275, 279 

in Sher. chart 270, 271 

in tinning 115, 117, 118 

of hydrofluoric acid pickle.. 49 
of molten zinc. Effect of at- 
mospheric conditions on.... 39 

of tin for coating on 39 

of tin for coating gray iron 

castings 117, 141, 142, 144 

Methods of calculating num- 
ber of degrees drop per hr. 
in molten zinc while cool- 
ing 38 

Natural actions in tank en- 
abling experts to accurate- 
ly judge 37 

of zinc required to secure un- 
iform coatings by hot pro- 
cess 35 

Regulating by pyrometer 34 

Too much heat destroys 

kettle 37 

Variation aff"ect tests 297 

Temperatures determined by 

color of zinc, etc 68 

Test, Caustic soda 293, 303 

Cinder for Galv. coating 225 

Copper sulphate or Preece, 

290, 294, 301 
for neutral Elec.-Galv bath 223 
for thickness of zinc coating 
on armored cable strip.... 226 

Government 303 

Hydrochloric acid and anti- 

'mony 308 

Lead acetate 291, 299 

Lead acetate, Advantages of 301 

Moist air - 226 

of hydrofluoric acid pickle.... 263 



326 



INDEX 



Test, Preece 290, 294, 301 

Pure water for Galv. coat- 
ing 225 

Salt spray 225, 304 

Sulphate of copper. 226 

Sulphuric acid for Galv. coat- 
ing 225 

Zinc coating 226, 287, 312 

Testing box. Salt spray 309 

Salt spray, Details of 311 

Material for mfr. of Hot 

Galv. kettles 19 

Zinc dust for metallic con- 
tent 258 

Tests, Galvanizing 288 

Comparative 225, 304-307 

Percentage of error due to 

temp, variations 297 

Preece and lead acetate 

compared 301 

Used to determine strength 

of wire 79 

Theory of Corrosion 11 

Thermometer, Method of using 39 

Time required for testing 292 

required for Sher...257, 272, 275 

required for tumbling 55-57 

required in Hot. Galv 69 

required in Elec.-Galv. 218, 

219, 223 
required to clean sandy gray 

iron castings 135 

Tin, "Boiling" to prevent dross 

from interfering with workl27 
Coating applied in a molten 

spray 94 

Dipping gray iron castings 

in 138 

not electro positive 12 

Proper temp, of 117 

Surplus, Method of remov- 
ing 118 

Surplus, Removal of in "skin- 
ning" kettle 127 

Surplus, Removing from wire 

tinned in coils 119 

Temp, of 106, 115, 118 

Tinned work. Old refinishing- 146 

Tinning, Applying the coating 115 

castings Math three kettles 

of tin 144 

Fuel for 107 

gray iron. Plant and equip- 
ment for - 129 

gray iron castings 129, 138 

gray iron castings, Flux for 138 
Gray iron castings must be 

absolutely clean for 136 

gray iron castings. Prepar- 
ing work for 133 



Tinning, gray iron castings, 
Proper heat for... .138, 141, 144 
gray iron castings. Time re- 
quired 138, 141 

iron spoons 109 

kettle. Flux for 139 

kettles. Materials used in con- 
structing 144 

malleable iron castings 106 

Passing work through kettle 117 
Plant and equipment 106, 

130, 144 

Plant, Drainage of 109, 130 

Plant for gray iron castings 130 

Preparing work for Ill 

Steel 106 

Steel spoons 119 

Time to prepare castings for 59 

Tools and kettles for 109, 116 

Wire in coils 119 

with two kettles 116 

Wrought iron 106 

Tongs 31 

for re-tinning. Construction 

of 127 

Proper use of 70 

Self-acting, on Hot Galv. ma- 
chine 75 

Use of in Hot Galv. sheets.... 73 

for Hot Galv 31 

for tinning 109-116, 119, 142, 143 
Tragacanth, Gum, in Elec.- 
Galv 221 

Its effect on Elec.-Galv. bath 222 
Transfer car, Construction of 253 

Trucks, Transfer 233 

Tube and Pipe Galv. Machine, 
Hanson and Van Winkle.. 189 

Galv. Machine, Potthoff 191 

Tubes, Automatic Galv. of 81 

Comparison of cost of Galv. 

by hand vs. machine 83 

Handling of to prevent trap- 
ping of air while Elec.- 
Galv 194 

Hot Galv. of - 77 

Machine for Hot Galv 82 

(Tubing Furnace for Sher 248 

Tumbling 51, 113, 136, 213 

and sand blasting 149, 213 

Tumbling Barrel, Charging 213 

Construction of ._.... 53 

Leaving work in it over night 56 

Loading of 54 

New cleaning preparatory to 

using 57 

Operation of 54, 136 

Recharging of 55 

Rev. per Min 61 

Solution for cleaning cast- 
ings 55, 57 



INDEX 



327 



Tumbling; Barrel 

Speed for cleaning castings 

55, 57, 60 
Time required to clean work 

in 55 

Tumbling Dry 52, 209, 213, 283 

Dry, of wire work 213 

Gray iron castings 133 

Time required for 55, 57 

U 

Under pickling 45 

Unloading and cooling drums 276 

Elec.-Galv. barrel 168, 173 

Unskilled labor in Hot Galv... 13 

V 

Vacuum, Slier, with zinc under 272 
Vapor, Effect of free ions on 

precipitation 230 

Precipitation of 229 

Tension 230, 231, 270 

Zinc, Methods of producing.. 230 
Vegetable cutters, Tinning of 129 
Ventilation of Hot Galv. plant 14 

of sand blasting room 62 

Voltage 193, 223 

differences 153 

for Elec. Cleaner 216 

for Elec.-Galv 218 

Proportioning of 207 

W 
Washer foundation. Cast iron 25 

Washing tank 165 

Water heater, Coating by 

Schoop process 104 

Rolling 51, 61, 113, 136 

Rolling gives better finish.. 58 

Tanks, Construction of 30 

tanks for tinning plant 108 

Watrous machine 72 

Wet rolling barrel gives better 

appearance to work 58 

Whipping box for tinning 108 

White pickling 46 

Winter, Dr. Heinrich, Paper 

on strength of wire 78 

Wire Cloth Elec.-Galv. Ma- 
chine King's 194 

Formula for Elec.-Galv. of 218 

Machine for Hot Galv 77 

Machine, Root's 202 

Hot Galv. of.- 77 

Influence of Galv.on strength 78 
Wire Netting, Elec.-Galv of.... 194 

Hot Galv. of 77 

Wire, Schulte machine for Elec. 

Galv 204 

Sher. test of 296 

Test 308, 310 

Testing samples 288 



Wire, Tinning in coils 119 

work. Dry tumbling of 213 

Wiring diagram, for Elec. 
heated Sher. furnace..249, 250 

Wrought iron pickling 48 

pipe. Temperature for Hot 

Galv 68 

Tinning of 106 



Zinc, ammonium, chloride better 
than sal ammoniac 42 

Zinc ashes 84 

Method of recovering 90 

Recovery of fine not profit- 
able 91 

Screening of a good practice 91 
Storage of 90, 91 

Zinc best rust preventive 11 

Boiling point of 272 

Chloride in Elec.-Galv. solu- 
tion 218, 219, 220, 221 

Zinc coating applied in a molten 

spray 94 

by Elec.-Galv. process 148 

Cost of by Schoop process.... 102 
Schoop metal spraying pistol 90 

Spec, for 287 

Table of tests on Elec.-Galv. 304 

Thickness of 267 

Thickness of in Schoop pro- 
cess 102 

Zinc colors indicate tempera- 
tures 68 

Corrosion saves the iron 12 

Deposit on sheets by Health- 
field process 76 

Zinc dross 256 

cooling in kettle bursts it.... 86 

Hard 84 

Kettle for recovering 87 

Method of recovery 85 

sweating or running over.... 88 
sweating 87 

Zinc dust 256 

Analysis of 274 

Color no proof of coating.... 281 
Cost per ton of Sher. ma- 
terial 284 

Drying out 257 

Fire in. How to put out 281 

Freeing it from iron 257 

Metallic content 267 

Determining metallic zinc... 258 

Oxidation of 274 

Oxidizes when sawdust or 

excelsior is mixed in 281 

Properties of 274 

Receptacle for 233 

Saving of 281 

Storage of 266 



328 



INDEX 



Zinc Dust, Used, Disposal 285 

Zinc electro positive to iron.... 11 

Iron alloy 227 

Melting point 35 

Melting point, Schoop process 99 

Overheating, Loss from 67 

Oxide Value of in Sher 231 

Oxidizing prevented to flux 69 
Pure, gives best Sher, re- 
sults - 231 

Residue, Disposal of 285 

Skimmings, Dry 84 

Slab or spelter 41 



Strike 223 

Sulphate in Elec.-Galv. solu- 
tion _ 218, 219, 220, 221, 222 

Zinc Surplus, Removal of 70-71 

Removal of by Porter ma- 
chine 71 

.Removal by Watrous machine 72 
Removal of from wire cloth 77 

Zinc, Temp, of 67 

Under vacuum, Sher. with.... 272 
Vapor, Methods of produc- 
ing 230 



267 90 












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